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Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly
European Journal of Paediatric Neurology xxx (xxxx) xxx
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European Journal of Paediatric Neurology
Original article
Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly Qingxian Chang a, *, Yanping Yang a, Yixian Peng a, Siping Liu b, Liyan Li b, Xujie Deng a, Ming Yang c, Yu Lan d a
Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China c Department of Pediatrics, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China d Department of Obstetrics and Gynecology, Guangzhou Red Cross Hospital Affiliated to Jinan University, Guangzhou, Guangdong, China b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 16 October 2019 Received in revised form 3 January 2020 Accepted 20 January 2020
Objectives: To systematically investigate chromosomal abnormalities and copy number variants (CNVs) in fetuses with different types of ventriculomegaly (VM) by karyotyping and/or chromosomal microarray analysis (CMA). Methods: This retrospective study included 312 fetuses diagnosed with VM. Amniotic fluid and umbilical blood samples were collected by amniocentesis and cordocentesis, respectively, and subjected to karyotyping and/or CMA. Subgroup analysis by VM type, including mild VM (MVM) and severe VM (SVM), unilateral and bilateral VM, isolated VM (IVM), and non-isolated VM (NIVM), was performed. Results: The detection rate of chromosomal abnormalities was 12.1% (34/281) by karyotyping and 20.6% when CMA was additionally performed (P < 0.05). Abnormalities were identified by CMA in 17.4% (38/ 218) of fetuses and pathogenic CNVs in 5.0% (11/218). Notably, CMA detected CNVs in 10.6% (23/218) of fetuses with normal karyotypes. The incidence of chromosomal abnormalities by karyotyping was higher in bilateral than in unilateral VM (20.5% versus 6.5%), whereas the incidence detected by CMA was higher in NIVM than in IVM (21.4% versus 10.3%; both P < 0.05). In NIVM, CMA provided an additional detection rate of 11.4% (16/140) and a detection rate of 10.0% for pathogenic CNVs and aneuploidies. Central nervous system (CNS) abnormalities were the most common other ultrasonic abnormalities. Conclusions: CMA is highly recommended for prenatal diagnosis of fetal VM together with karyotyping, especially in fetuses with bilateral VM and NIVM with abnormal CNS findings. Further study is necessary to explore the relationships between genotypes and phenotypes to facilitate prenatal diagnosis of fetal VM. © 2020 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Fetal ventriculomegaly Prenatal diagnosis Chromosomal microarray analysis Copy number variants Karyotype
1. Introduction Fetal ventriculomegaly (VM), defined as a lateral ventricle diameter of 10 mm, is a common cerebral abnormality detected during prenatal ultrasound screening [1], with reported incidence of 0.03e1% [1,2]. Fetal VM can be classified as mild (10e15 mm,
Abbreviations: VM, ventriculomegaly; CMA, chromosomal microarray analysis; CNV, copy number variant; CNS, central nervous system. * Corresponding author. Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 Guangzhou Avenue North, Guangzhou, 510515, Guangdong, China. E-mail address: [email protected] (Q. Chang).
MVM) or severe (15 mm, SVM) VM or hydrocephalus [1]; unilateral or bilateral VM; and isolated (only VM, IVM) or non-isolated VM (plus other ultrasonic abnormalities, NIVM) [2]. MVM has been suggested to increase the risk of neurodevelopmental disorders such as autism, epilepsy, and psychomotor disorders [3]. The etiology includes chromosomal or structural abnormalities and congenital infections [1]; however, the exact causes remain unknown. Chromosomal abnormalities occur in 5%e10.2% of fetuses with IVM and the incidence can increase to 18% in NIVM with other structural abnormalities, such as choroid plexus cysts and callosal agenesis [4,5]. Because of the diverse causes and prognosis of the different types of VM, genetic counseling and prenatal diagnosis of fetal VM
https://doi.org/10.1016/j.ejpn.2020.01.016 1090-3798/© 2020 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
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are challenging in clinical practice. Karyotyping remains the gold standard for detecting chromosomal abnormalities in fetal VM. However, it is limited in detecting abnormalities larger than 5 Mb and cannot identify copy number variants (CNVs) such as 16q12.1 deletion and 22q11.2 duplication [6,7], which are associated with fetal VM. Chromosomal microarray analysis (CMA), characterized by high-resolution and whole-genome, not only can identify numerical chromosomal abnormalities, as can karyotyping, but can also provide an additional diagnostic yield by revealing imbalances or submicroscopic CNVs at a kilobase level that are not detectable by routine karyotyping [8]. CMA has thus become the first-tier diagnostic tool for genetic evaluation of neurodevelopmental disorders, mental retardation, and spontaneous miscarriage [9e11]. The American College of Obstetricians and Gynecologists recommends prenatal diagnosis by CMA rather than karyotyping when fetuses show structural ultrasonic abnormalities [12]. Some studies have applied CMA for prenatal diagnosis of fetal central nervous system (CNS) abnormalities, including VM; however, the sample size for fetal VM was small or the focus was on anomalies other than VM, and results on the diagnostic yield of CMA and/or karyotyping for fetal VM were variable [6,7]. Therefore, in this retrospective study, we systematically investigated the distribution and further evaluated the detection rates of chromosome abnormalities or CNVs in fetuses with different types of VM by karyotyping and/or CMA to provide better prenatal counseling and perinatal management. 2. Methods 2.1. Subjects This study was performed in Nanfang Hospital affiliated to Southern Medical University. Between January 2014 and June 2019, 312 pregnancies with fetal VM, either with or without other structural anomalies, were referred for prenatal consulting and diagnosis at the Prenatal Diagnostic Center. The diagnosis of fetal VM was confirmed at our hospital. After the exclusion of twin pregnancies and failure of paracentesis or cell culture, 281 singleton fetuses with VM were included, who underwent prenatal diagnosis by karyotyping and/or CMA. All the subjects, aged 19e44 years, received prenatal consulting and provided written informed consent before the invasive procedure was performed. The median gestational age at the time of the procedure was 26.4 ± 4.0 weeks (range, 15þ6 to 37þ2). The results of prenatal diagnosis were recorded, and pregnancy outcomes were followed up. The study was approved by the ethics committee of Nanfang Hospital affiliated to Southern Medical University (NFEC-2017-035). 2.2. Ultrasonic examination Ultrasonic examination for fetal VM was conducted transabdominally with a 2.5e5.0-MHz probe (Version 730 Expert and E8; GE Medical Systems, Zipf, Austria) by experienced operators, with measurements recorded in the standard planes according to the International Society of Ultrasound in Obstetrics and Gynecology guidelines [13]. Fetal VM was defined as a uni- or bilateral lateral ventricle width 10 mm and was classified as MVM, SVM, or hydrocephalus; unilateral or bilateral VM; IVM or NIVM, as described [2,14]. 2.3. Sample collection According to the gestational week, amniotic fluid and umbilical blood samples were collected by ultrasound-guided transabdominal amniocentesis and cordocentesis, respectively. Thirty
milliliters of amniotic fluid or 3 mL of umbilical blood was extracted for karyotyping and CMA. Parental peripheral blood samples were collected to exclude maternal contamination and were used for auxiliary interpretation of the CNVs when necessary.
2.4. Karyotyping Karyotyping was conducted following standard protocols for cultured amniocytes or blood cells using standard G-banding [15]. At least 20 metaphase cells were counted, and five metaphase cells were examined to detect numerical and structural chromosomal abnormalities.
2.5. CMA and data analysis Fetal genomic DNA was extracted from cultured cells using the QIAamp DNA Mini Kit (Qiagen, Hilden, Germany). CMA was carried out using Infinium™ OmniZhongHua-8 v1.3 BeadChips (Illumina, Inc., San Diego, CA, USA). DNA amplification, hybridization, and analysis were carried out as per the manufacturer's instructions. Whole-genome BeadChip scan data were analyzed with KaryoStudio software and annotated to the reference genome GRCH37 (hg19). CNVs of unknown significance smaller than 500-kb deletion, 1-Mb duplication, or 10-Mb loss of heterozygosity (LOH) were not reported [16]. The clinical significance of the detected CNVs was interpreted based on information in databases and academic publications. The following databases were used: Database of Genomic Variants (DGV, http://dgv.tcag.ca/dgv/), International Standards for Cytogenomic Arrays (ISCA, http://www.iscaconsortium.org/), Online Mendelian Inheritance in Man (OMIM, http://www.ncbi.nlm.nih. gov/omim), Chromosomal Imbalance and Phenotype in Humans Using Ensemble Resources (DECIPHER, https://decipher.sanger.ac. uk/), University of California Santa Cruz Genomic Browser (UCSC, http://genome.ucsc.edu/), and PubMed (https://www.ncbi.nlm.nih. gov/pubmed/). Based on guidelines of the American College of Medical Genetics [17], the CNVs in this study were classified into pathogenic (P), benign (B), or variants of uncertain significance (VOUS/V). DNA extracted from parental peripheral blood samples was subjected to CMA to analyze whether the detected fetal CNVs were inherited or de novo.
2.6. Statistical analyses Data were analyzed using SPSS software (version 20.0, IBM, Armonk, NY, USA). Continuous variables are reported as the mean ± standard deviation (SD). Means were compared using Chisquare test, or Fisher's exact test. P-values < 0.05 were considered statistically significant.
3. Results The characteristics of the 281 singleton fetuses with VM are summarized in Table 1. The mean maternal age was 29.0 ± 5.0 years, and the mean gestational age was 26.4 ± 4.0 weeks. Fortyfive subjects (16.0%) had an advanced maternal age (35 years old). CMA was conducted in addition to karyotyping for 218 (77.6%) fetuses. The detection rate of chromosomal abnormalities by karyotyping was 12.1% (34/281), whereas it was 20.6% (58/281) when CMA was also conducted (c2 ¼ 7.486, P ¼ 0.006).
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
Q. Chang et al. / European Journal of Paediatric Neurology xxx (xxxx) xxx
3.2. Distribution of chromosomal abnormalities and detection rates in 218 cases by karyotyping and CMA
Table 1 Characteristics of 281 singleton fetuses with ventriculomegaly. Characteristic MA (years) <35 35 Mean Mean GA (weeks) at detection Parity Nulliparous Parous Method of sampling Amniocentesis (A) Umbilical blood sampling (U) Detection method Karyotyping only Karyotyping plus CMA Total detected positive rates Karyotyping Karyotyping plus CMA
n
n (%)
236 45 29.0 ± 5.0 26.4 ± 4.0
84.0% 16.0% e e
123 158
43.8% 56.2%
205 76
73.0% 27.0%
63 218
22.4% 77.6%
34 58
12.1% 20.6%
3
c2
P
7.486
0.006*
MA, maternal age; GA, gestational age; CMA, chromosomal microarray analysis; c2, Chi-square test value. *P < 0.05.
3.1. Chromosomal abnormalities and CNVs detected in fetuses with VM As shown in Table 2, 34 (12.1%) fetuses with VM were found to have chromosomal abnormalities by karyotyping, including 16 aneuploidies and 18 other abnormalities. Trisomy 21 was the most common aneuploidy (n ¼ 10), and trisomy 18, trisomy 13, 47, XXX, 47, XYY, and triploidy were also detected. Other abnormalities included 46, XN, inv (9) (p12q13), 46, X, inv(Y) (p11.2q11.2) and so on. In subgroup analysis, chromosomal abnormalities were significantly more abundant in bilateral fetal VM than in unilateral VM (20.5% versus 6.5%; P < 0.05). However, we observed no significant differences in chromosomal abnormalities between MVM and SVM, nor between IVM and NIVM (both P > 0.05). Chromosomal abnormalities were detected by CMA in 17.4% of cases (Table 3), including five aneuploidies and 33 CNVs; this detection rate was higher than that by karyotyping. In particular, pathogenic CNVs were identified in 11 out of 218 (5.0%) cases. Seventeen cases were found to have benign CNVs, and five cases had VOUS or LOH. No significant differences were found between MVM (17.8%) and SVM (10.0%), or between unilateral VM (13.5%) and bilateral VM (22.8%). However, the detection rate by CMA was significantly different between NIVM (21.4%) and IVM (10.3%) (P < 0.05). In general, CMA had a higher positive detection rate of chromosomal abnormalities than karyotyping for most VM types.
As shown in Table 4, the overall detection rate of chromosomal abnormalities in fetal VM by CMA was 17.4%, whereas that of karyotyping was 9.6% (P < 0.05). Notably, CNVs were detected by CMA in 23 fetuses with normal karyotypes, suggesting a 10.6% additional diagnostic value. As for the different VM types, detection rates were significantly different between karyotyping and CMA in the MVM, unilateral VM, and NIVM groups (all P < 0.05), with additional detection rates of 11.1e11.9%. In 140 fetuses with NIVM (Table 5), CMA showed a significantly higher detection rate than did karyotyping (21.4% versus 11.4%, P < 0.05). Fourteen (10.0%) pathogenic CNVs and aneuploidies were detected among 140 fetuses with NIVM, eight of whom exhibited CNS abnormalities, and 16 (11.4%) CNVs were benign or VOUS. In addition, CMA had significant benefits over karyotyping in cases of fetal VM with single-system abnormal ultrasound findings. Fetal VM was often detected in association with other abnormal ultrasound findings, mainly of the CNS (n ¼ 73), followed by the cardiovascular system (n ¼ 48), including dilatation of posterior fossa cistern, agenesis of the corpus callosum, and intracardiac echogenic foci. 3.3. CNVs detected by CMA in 23 fetuses with VM and pregnancy outcomes As shown in Table 6, 23 fetuses had normal karyotypes, but CNVs, including 14 duplications, eight deletions, and one LOH. Clinically significant pathogenic CNVs were identified in three fetuses, indicating a 1.4% (3/218) incremental yield by CMA; two of these fetuses had NIVM with CNS and CVS malformations, and one had unilateral IVM. All these pregnancies were terminated. Two pregnancies opted for TOP because of multiple fetal CNS malformations. LOH on chromosome 7q21.1 was detected in Case 31, with unclear clinical significance. The remaining 17 cases had benign CNVs or VOUS, and the mothers continued the pregnancy and had live births by delivery or cesarean section. 4. Discussion To systematically investigate the distribution and further evaluate the detection rates of chromosomal abnormalities or CNVs in fetuses with different types of VM by karyotyping and/or CMA, we conducted a retrospective study of 312 fetuses with VM. The results suggested that CMA effectively improved the detection rates in bilateral and NIVM with CNS abnormalities over karyotyping, with an additional diagnostic rate of 10.6% in fetuses with normal
Table 2 Distribution of chromosomal abnormalities in fetuses with ventriculomegaly detected by karyotyping (n ¼ 281). Karyotyping
Total
Mild
Severe
Unilateral
Bilateral
Isolated
Non-isolated
Number (%) Trisomy 21 Trisomy 18 Trisomy 13 47, XXX 47, XYY Triploidy Others Positive (n) P, rates (%)
281 10 1 2 1 1 1 18 34 12.1%
271 (96.4%) 9 1 2 1 1 1 17 32 11.8% 0.606 0.346
10 (3.6%) 1 0 0 0 0 0 1 2 20%
169 (60.1%) 1 1 1 1 1 1 5 11 6.5% 12.461 0.000*
112 (39.9%) 9 0 1 0 0 0 13 23 20.5%
99 (35.2%) 2 0 0 1 0 0 4 7 7.1% 3.653 0.057
182 (64.8%) 8 1 2 0 1 1 14 27 14.8%
c2 P *P < 0.05.
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
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Table 3 Distribution of chromosomal abnormalities in fetuses with ventriculomegaly detected by CMA (n ¼ 218). CMA
Total
Mild
Severe
Unilateral
Bilateral
Isolated
Non-isolated
Number (%) Trisomy 21 Trisomy 13 Deletion Duplication Pathogenic Benign VOUS/LOH Positive (n) P, rate (%)
218 4 1 19 19 11 17 5 38 17.4%
208 (95.4%) 3 1 19 19 11 17 5 37 17.8% 0.040 1.000
10 (4.6%) 1 0 0 0 0 0 0 1 10.0%
126 (57.8%) 0 0 6 10 4 9 4 17 13.5% 3.219 0.073
92 (42.2%) 4 1 13 9 7 8 1 21 22.8%
78 (35.8%) 1 0 3 4 1 4 2 8 10.3% 4.344 0.037*
140 (64.2%) 3 1 16 15 10 13 3 30 21.4%
c2 P
CMA, chromosomal microarray analysis; VOUS, variants of uncertain significance; LOH, loss of heterozygosity. *P < 0.05.
Table 4 Comparison of detection rates in fetal ventriculomegaly by karyotyping and CMA (n ¼ 218). Detection rates of chromosomal abnormalities Types
Mild Severe Unilateral Bilateral Isolated Non-isolated Total
N
208 10 126 92 78 140 218
Karyotyping
CMA
Added
n (%)
n (%)
n (%)
19(9.1) 2(20.0) 4(3.2) 17(18.5) 5(6.4) 16(11.4) 21(9.6)
37(17.8) 1(10.0) 17(13.5) 21(22.8) 8(10.3) 30(21.4) 38(17.4)
23(11.1) 0 15(11.9) 8(8.7) 7(9.0) 16(11.4) 23(10.6)
c2
P
6.686 0.373 8.744 0.531 0.755 5.098 5.665
0.010* 1.000 0.005* 0.466 0.385 0.024* 0.017*
CMA, chromosomal microarray analysis. *P < 0.05 (karyotyping vs. CMA).
karyotypes, and of 5.0% in fetuses with pathogenic CNVs. Several deletions or duplications found in fetal VM have been associated with neurodevelopmental disorders. VM is detected in 1% of fetuses during prenatal ultrasonography and reportedly is linked to cognitive, language, and behavioral dysfunctions in childhood [18]. A recent study suggested that mild IVM is related to an increased risk of neurodevelopmental disorders, including autism and schizophrenia, in children [3]. Adverse neurodevelopmental outcomes occur in 7.9% of fetuses with mild IVM, and the prevalence may increase to 38e90% in fetuses with
severe IVM or hydrocephalus [4,19]. However, the association between fetal VM and the risk of adverse neurodevelopmental outcomes is controversial as the overall incidence of neurodevelopmental adversities in the general population is similar, and thus, large-cohort prospective studies are needed. Chromosomal abnormality is a common cause of fetal VM, with an incidence of 5e8.3% [2]. Owing to the complex causes, comprehensive evaluation and prenatal diagnosis by karyotyping and CMA are highly recommended when fetal VM is identified [3]. An abnormal karyotype, most commonly, trisomy 21 [20], is detected in approximately 5% of fetuses with MVM, and in 6.8% of fetuses with SVM [21]. In this study, the total detection rate of chromosomal abnormalities by karyotyping was 12.1%, with incidence rates of 11.8% for MVM and 20.0% for SVM, which were higher than those reported in previous studies [20,21]. This might be explained by different cut-offs for VM, combination with other ultrasound findings, or the high risk of serological screening. Chromosomal abnormalities were more common in bilateral than in unilateral VM. However, there was no significant difference in the incidence of abnormal karyotypes regardless of the severity of fetal VM or the presence of other ultrasound findings. Given its high resolution in detecting CNVs, CMA has a significantly higher detection rate for chromosomal aberrations than routine karyotyping has [22]. In this study, CMA identified chromosomal abnormalities in 17.4% of cases (38/218), including CNVs in 33 (15.4%) cases of fetal VM, which was higher than the number found by karyotyping (12.4%, 34/281). The detection rate for total
Table 5 Chromosomal abnormalities and detection rates in fetuses with non-isolated ventriculomegaly. Karyotyping
US findings
N
Total Single system 2 systems CNS CVS Digestive system AF Urinary system Skeletal system NF Others
140 80 60 73 48 23 19 18 15 10 26
CMA
Positive n (%)
T21 T13
Others
Positive n%
P
B/V
16(11.4) 6(7.5) 10(16.7) 8(11.0) 8(16.7) 3(13.0) 2(10.5) 3(16.7) 7(46.7) 3(30.0) 6(23.1)
4 1 3 2 2 1 1 1 2 1 1
12 5 7 6 6 2 1 2 5 2 5
30(21.4) 15(18.75) 15(25.0) 18(24.7) 10(20.8) 5(21.7) 3(15.8) 5(27.8) 7(46.7) 4(40.0) 7(26.9)
14 5 9 8 6 3 2 3 5 2 5
16 10 6 10 4 2 1 2 2 2 2
Added n%
c2
P
16(11.4) 10(12.5) 6(10.0) 11(15.1) 3(6.3) 2(8.7) 1(5.3) 2(11.1) 1(6.7) 1(10.0) 2(7.7)
5.098 4.440 1.263 4.679 0.274 0.592 0.224 0.625 0.000 0.209 0.103
0.024* 0.035* 0.261 0.031* 0.601 0.699 1.000 0.891 1.000 1.000 0.749
Others include increased S/D ratio (n ¼ 6), facial anomaly (n ¼ 5), fetal growth restriction (n ¼ 5), persistent right umbilical vein (n ¼ 4), single umbilical artery (n ¼ 3), abnormal external genital morphology (n ¼ 2), hydrocele (n ¼ 1) and dilation of the intrahepatic segment of umbilical vein (n ¼ 1). US, ultrasound; AF, amniotic fluid; P, pathogenic (including aneuploidies); B, benign; V, VOUS; NF, nuchal fold; CNS, central nervous system; CVS, cardiovascular system; CMA: chromosomal microarray analysis. *P < 0.05 (karyotyping vs. CMA).
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
Q. Chang et al. / European Journal of Paediatric Neurology xxx (xxxx) xxx
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Table 6 CNVs detected by CMA and pregnancy outcomes in 23 fetuses with ventriculomegaly. Case GA 1 2 3 4 5 6 7 8 9 10 11
12 13 14 15 16
17 18 19 20 21 22
23
U/ CMA A
35þ5 U arr[hg19]18p11p11.23(7,024,998 e7,578,782) 3 25þ4 A arr[hg19]11p15.4(5,487,596 e5,69,0691) 1 24þ1 A arr[hg19]15q11.2(22,754,322 e23,222,284) 1 25 A arr[hg19]2p24.3(13,579,747 e14,334,195) 3 23þ6 A arr[hg19]2q13(110,863,908 e110,982,530) 3 24þ2 A arr[hg19]2p25.2p25.3(4,124,656 e4,641,479) 1 28þ5 U arr[hg19] 8p23.2(2,355,745 2,801,788) 3 29þ6 U arr[hg19]19p12(22,363,682 e23,195,094) 3 25þ2 A arr[hg19]7q11.1(61,074,194 e62,935,337) 3 33þ4 U arr[hg19]15q22.31q23(66,981,329 e68,050,777) 1 28þ4 U arr[hg19]11p12(40,966,294 e43,095,376) 1; arr[hg19] Xp22.2p22.13(16,950,577 e17,711,019) 3
Size
Type
Karyotyping Ultrasound findings
Outcome
553 kb
Duplication
Normal
CS
203 kb
Deletion
467 kb
Normal
Unilateral VM; Posterior fossa cistern widened; Dilation of the third ventricle Bilateral VM
CS
Deletion
Normal
Unilateral VM; Thickened nuchal fold
CS
736 kb
Duplication
Normal
Unilateral VM; Posterior fossa cistern cyst
CS
118 kb
Duplication
Normal
Unilateral VM; Choroid plexus cyst
CS
517 kb
Deletion
Normal
Delivery
446 kb
Duplication
Normal
Bilateral VM; Posterior fossa cistern cyst; Bilateral renal pelvis separation Bilateral VM; Ependymal cyst; Echogenic bowel; Bowel dilation
Delivery
831 kb
Duplication (paternal) Duplication
Normal
Unilateral VM
Delivery
Normal
Unilateral VM; Nasal bone dysplasia
Delivery
1.07 Mb
Bilateral VM; Ascending aorta dilation; S/D ratio increased
TOP
24þ4 A arr[hg19]10q26.3(134,987,109 e135,135,377,570) 3 30þ1 U arr[hg19]16p13.11p13.12(14,760,734 e16,303,388) 1 27þ3 A arr[hg19]7q11.23(72,305,671 e75,067,967) 3 37þ1 A arr[hg19]21q11.2(14,368,320 e15,696,202) 3 33þ1 U arr[hg19]2q12.2q12.3(106,878,354 e108,440,138) 3; arr[hg19] 6q21(111,673,714e112,732,041) 3 32þ3 A arr[hg19]17q24.1q25.3(62,781,579 e81,051,007) 3 33 U arr[hg19]19p13.3(2,888,242 e3,664,094) 1 23þ4 A arr[hg19]6q25.2(152,689,195 e153,226,106) 1 32þ3 A arr[hg19]15q11.1q11.2(20,161,372 e23,086,929) 3 24þ4 A arr[hg19]7q21.1(78,463,648 e92,558,612) 2hmz 24þ6 A arr[hg19]16p13.11(14,968,859 e16,291,983) 1
390 kb
Duplication
TOP Bilateral VM; Posterior fossa cistern cyst; Dilation of the fourth ventricle; Cavum vergae cyst; Cerebellum dysplasia; Cardiomegaly; Tricuspid regurgitation; Pulmonary valve stenosis with regurgitation; Foramen ovale dilation; Fetal growth restriction; Echogenic bowel Unilateral VM CS
1.54 Mb
Deletion Normal (pathogenic) Duplication Normal (pathogenic) Duplication Normal
Unilateral VM; Choroid plexus cyst; Cavum septum pellucidum cyst Unilateral VM
TOP
Bilateral VM
CS
1.56 M; 1.06 Mb
Duplication
Normal
Unilateral VM; Posterior fossa cistern widened; Polyhydramnios
CS
18.3 Mb
Duplication
Normal
TOP
775 kb
Normal Normal
Delivery
2.93 Mb
Deletion (VOUS) Deletion (VOUS) Duplication
Unilateral VM; Cerebellum dysplasia; Posterior fossa cistern widened; Arachnoid cyst; Unilateral VM; Posterior fossa cistern widened; Dilation of the third ventricle Unilateral VM
Normal
Bilateral VM; Left hydronephrosis with ureteral dilatation
Delivery
14.1 Mb
LOH (VOUS) Normal
CS
1.32 Mb
Normal
CS
31þ6 U arr[hg19]15q21.3q22.2(58,801,234 e60,474,270) 3
1.67 Mb
Deletion (VOUS) (parents' normal) Duplication (VOUS)
Unilateral VM; Cavum septum pellucidum disappeared and the anterior horn and body of the lateral ventricle fused Bilateral VM
Normal
Unilateral VM; Ventricular bright spot; Fetal growth restriction
CS
1.86 Mb
Deletion Normal (pathogenic) 2.13 Mb; Deletion; Normal 760 kb Duplication
2.76 Mb 1.33 Mb
536 kb
Normal
TOP
CS
This table does not include chromosome aneuploidy. GA, gestational age; A, amniocentesis; U, umbilical cord blood puncture; CMA, chromosomal microarray analysis; CS, caesarean section; TOP, termination of pregnancy; LOH, loss of heterozygosity; VOUS, variants of uncertain significance; S/D ratio, the ratio of fetal umbilical artery systolic blood pressure to diastolic blood pressure.
pathogenic CNVs in fetal VM was 5.0% (11/218), which was similar to the reported detection rate of 5.1% in mild to severe VM [23]. Several pathogenic CNVs, such as deletions of 21q22.11, 22q12.1q12.3, and 6q27, were identified, which have been reported in cases with MardeneWalker syndrome [24], agenesis of the corpus callosum [25], and structural brain abnormalities including hydrocephalus and cerebellar malformations [26], respectively. In the subgroup analysis, the increase in the diagnostic yield was significantly higher with CMA than with routine karyotyping for MVM, unilateral VM, and NIVM, ranging from 11.1% to 11.9%. Pathogenic CNVs were detected in 7.1% (10/140) fetuses with NIVM, which is higher than the rate (6.6%) reported previously [23]. CNS
abnormality was the most common additional structural finding, in line with a previous report [5]. Together, these results indicate that in general, CMA is preferable over karyotyping for the detection of abnormal genomic variants in fetal VM. In fetuses with normal karyotypes, CMA detects clinically significant CNVs in 1e6% of pregnancies [8]. Similarly, in our study, CMA had an additional diagnostic yield of 10.6% (23/218) in detecting abnormalities in fetal VM with normal karyotypes, 1.4% (3/218) cases of which had clinically significant CNVs (summarized below) reported to be associated with neurodevelopmental disorders. Case 10 was a fetus with a 1.07-Mb 15q22.31q23 deletion, with
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
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bilateral NIVM, ascending aorta dilation, and increased S/D ratio on ultrasound. Deletion of 15q22.31 is reportedly associated with intellectual disability or developmental delay [9] and is considered to be pathogenic; therefore, the mother underwent elective TOP. Case 13 was a fetus with unilateral VM, choroid plexus cyst and cavum septum pellucidum cyst, and had a 1.54-MB 16p13.11p13.12 deletion. Deletion of 16p13.11 reportedly is associated with microcephaly, developmental delay, behavioral abnormalities, and impairments in social interaction [27], and is a genetic factor for epilepsy and other neurodevelopmental disorders [28]. A wide spectrum of other abnormalities, including autism, intellectual disability, and congenital anomalies such as cleft lip, facial dysmorphism, and even holoprosencephaly, have been reported as well [29]. Owing to the multiple abnormalities in CNS and the reported phenotypes, pregnancy was terminated in this case. Case 14, a fetus with unilateral VM had a 2.76-Mb duplication in chromosome 7q11.23. This duplication is significantly associated with autism and schizophrenia [30]. Intellectual disability, language delay, social anxiety, and behavioral difficulties have been reported in patients with 7q11.23 deletion [31]. Brain malformations, hydrocephalus, and craniofacial and cardiac abnormalities have been reported as well [31]. Though diagnosed as having unilateral IVM and a normal karyotype, TOP was opted for in this case due to the pathogenic CNV. CMA is a sensitive method for detecting whole-genome chromosomal abnormalities or CNVs in fetal VM, providing more information for prenatal consultation and selective birth [20]. However, CMA has its own limitations, such as the inability to detect balanced rearrangements or mosaicism [8]. Further, VOUS presents a challenge for genetic counseling and diagnosis [8]. Therefore, pre-test counseling is necessary to inform the parents on the benefits, limitations, and diagnostic scope of CMA over other prenatal methods. One limitation of this study was that not all fetuses with VM had undergone MRI examination for the final diagnosis of IVM or NIVM, which might affect the incidence of different types of fetal VM. MRI can detect an anomaly that is not identified on ultrasound in 10.0% of fetuses, which might influence the choice of TOP by the parents [32]. Moreover, this was a retrospective observational study and the follow-up time of fetuses was limited. However, through follow-up of the cases with CNVs but normal karyotypes after birth, we found that four (4/14, 28.6%) cases aged from one to five years old had certain language, motor, and mental retardation, including inability to speak fluently or unclear pronunciation and poor intelligence assessment results, when compared with children of the same age, which will help to explore clinical significance of CNVs. With longer follow-up time and more samples, more clinically significant phenotypes might be found in fetal VM with CNVs but normal karyotypes, so as to better explore the relationship between genetic etiology and clinical manifestations. 5. Conclusions Fetal VM is a common abnormal CNS finding on prenatal ultrasound. Chromosomal abnormalities and CNVs, some of which are related to neurodevelopmental disorders in infants or children, contribute to the etiology. Compared with conventional karyotyping, CMA improves the prenatal detection rates, with an additional detection rate of 10.6% in fetuses with normal karyotypes and 5.0% in fetuses with clinically pathogenic CNVs. CMA is highly recommended for prenatal diagnosis together with karyotyping in fetuses with VM, especially those with bilateral and NIVM combined with abnormal CNS findings. In the future, the relationship between genotypes and phenotypes needs to be explored so as to facilitate prenatal diagnosis of fetal VM.
Declaration of competing interest All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. There are no conflicts of interest to declare. Acknowledgements We thank all the participants involved in the study and our colleagues in the Prenatal Diagnosis Center and Department of Obstetrics and Gynecology. References [1] Society for Maternal-Fetal Medicine, N.S. Fox, A. Monteagudo, J.A. Kuller, S. Craigo, M.E. Norton, Mild fetal ventriculomegaly: diagnosis, evaluation, and management, Am. J. Obstet. Gynecol. 219 (2018), https://doi.org/10.1016/ j.ajog.2018.04.039. B2eB9. [2] T. Hannon, P.W. Tennant, J. Rankin, S.C. Robson, Epidemiology, natural history, progression, and postnatal outcome of severe fetal ventriculomegaly, Obstet. Gynecol. 120 (2012) 1345e1353, https://doi.org/10.1097/ aog.0b013e3182732b53. [3] E. Thorup, L.N. Jensen, G.S. Bak, et al., Neurodevelopmental disorder in children believed to have isolated mild ventriculomegaly prenatally, Ultrasound Obstet. Gynecol. 54 (2019) 182e189, https://doi.org/10.1002/uog.20111. [4] G. Pagani, B. Thilaganathan, F. Prefumo, Neurodevelopmental outcome in isolated mild fetal ventriculomegaly: systematic review and meta-analysis, Ultrasound Obstet. Gynecol. 44 (2014) 254e260, https://doi.org/10.1002/ uog.13364. [5] F. Sethna, P.W. Tennant, J. Rankin, C.R. S, Prevalence, natural history, and clinical outcome of mild to moderate ventriculomegaly, Obstet. Gynecol. 117 (2011) 867e876, https://doi.org/10.1097/AOG.0b013e3182117471. [6] M. Schumann, A. Hofmann, S.K. Krutzke, et al., Array-based molecular karyotyping in fetuses with isolated brain malformations identifies diseasecausing CNVs, J. Neurodev. Disord. 8 (2016) 11, https://doi.org/10.1186/ s11689-016-9144-y. [7] L. Sun, Q. Wu, S.W. Jiang, et al., Prenatal diagnosis of central nervous system anomalies by high-resolution chromosomal microarray analysis, BioMed Res. Int. 2015 (2015) 426379, https://doi.org/10.1155/2015/426379. [8] B. Levy, R. Wapner, Prenatal diagnosis by chromosomal microarray analysis, Fertil. Steril. 109 (2018) 201e212, https://doi.org/10.1016/ j.fertnstert.2018.01.005. [9] V. Peycheva, K. Kamenarova, N. Ivanova, et al., Chromosomal microarray analysis of Bulgarian patients with epilepsy and intellectual disability, Gene 667 (2018) 45e55, https://doi.org/10.1016/j.gene.2018.05.015. [10] S. Liu, L. Song, D.S. Cram, et al., Traditional karyotyping vs copy number variation sequencing for detection of chromosomal abnormalities associated with spontaneous miscarriage, Ultrasound Obstet. Gynecol. 46 (2015) 472e477, https://doi.org/10.1002/uog.14849. [11] T. Sahoo, N. Dzidic, M.N. Strecker, et al., Comprehensive genetic analysis of pregnancy loss by chromosomal microarrays: outcomes, benefits, and challenges, Genet. Med. 19 (2017) 83e89, https://doi.org/10.1038/gim.2016.69. [12] Committee Opinion No, 682 Summary: microarrays and next-generation sequencing technology: the use of advanced genetic diagnostic tools in obstetrics and gynecology, Obstet. Gynecol. 128 (2016) 1462e1463, https:// doi.org/10.1097/aog.0000000000001814. [13] International Society of Ultrasound in Obstetrics and Gynecology Education Committee, Sonographic examination of the fetal central nervous system: guidelines for performing the ‘basic examination’ and the ‘fetal neurosonogram’, Ultrasound Obstet. Gynecol. 29 (2007) 109e116, https://doi.org/ 10.1002/uog.3909. [14] B. Scelsa, M. Rustico, A. Righini, et al., Mild ventriculomegaly from fetal consultation to neurodevelopmental assessment: a single center experience and review of the literature, Eur. J. Paediatr. Neurol. 22 (2018) 919e928, https://doi.org/10.1002/uog.12403. [15] U. Francke, Clinical and molecular cytogenetics and gene mapping: principles and techniques, Southeast Asian J. Trop. Med. Publ. Health 26 (Suppl 1) (1995) 34e43. [16] C.M. Armour, S.D. Dougan, J.A. Brock, R. Chari, B.N. Chodirker, I. DeBie, J.A. Evans, W.T. Gibson, E. Kolomietz, T.N. Nelson, F. Tihy, M.A. Thomas, D.J. Stavropoulos, On-Behalf-Of the Canadian College of Medical Geneticists. Practice guideline: joint CCMG-SOGC recommendations for the use of chromosomal microarray analysis for prenatal diagnosis and assessment of fetal loss in Canada, J. Med. Genet. 55 (2018) 215e221, https://doi.org/10.1136/ jmedgenet-2017-105013. [17] H.M. Kearney, E.C. Thorland, K.K. Brown, F. Quintero-Rivera, S.T. South, Working Group of the American College of Medical Genetics Laboratory Quality Assurance Committee, American College of Medical Genetics standards and guidelines for interpretation and reporting of postnatal
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Contents lists available at ScienceDirect
European Journal of Paediatric Neurology
Original article
Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly Qingxian Chang a, *, Yanping Yang a, Yixian Peng a, Siping Liu b, Liyan Li b, Xujie Deng a, Ming Yang c, Yu Lan d a
Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China Technology Center of Prenatal Diagnosis and Genetic Diseases Diagnosis, Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China c Department of Pediatrics, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China d Department of Obstetrics and Gynecology, Guangzhou Red Cross Hospital Affiliated to Jinan University, Guangzhou, Guangdong, China b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 16 October 2019 Received in revised form 3 January 2020 Accepted 20 January 2020
Objectives: To systematically investigate chromosomal abnormalities and copy number variants (CNVs) in fetuses with different types of ventriculomegaly (VM) by karyotyping and/or chromosomal microarray analysis (CMA). Methods: This retrospective study included 312 fetuses diagnosed with VM. Amniotic fluid and umbilical blood samples were collected by amniocentesis and cordocentesis, respectively, and subjected to karyotyping and/or CMA. Subgroup analysis by VM type, including mild VM (MVM) and severe VM (SVM), unilateral and bilateral VM, isolated VM (IVM), and non-isolated VM (NIVM), was performed. Results: The detection rate of chromosomal abnormalities was 12.1% (34/281) by karyotyping and 20.6% when CMA was additionally performed (P < 0.05). Abnormalities were identified by CMA in 17.4% (38/ 218) of fetuses and pathogenic CNVs in 5.0% (11/218). Notably, CMA detected CNVs in 10.6% (23/218) of fetuses with normal karyotypes. The incidence of chromosomal abnormalities by karyotyping was higher in bilateral than in unilateral VM (20.5% versus 6.5%), whereas the incidence detected by CMA was higher in NIVM than in IVM (21.4% versus 10.3%; both P < 0.05). In NIVM, CMA provided an additional detection rate of 11.4% (16/140) and a detection rate of 10.0% for pathogenic CNVs and aneuploidies. Central nervous system (CNS) abnormalities were the most common other ultrasonic abnormalities. Conclusions: CMA is highly recommended for prenatal diagnosis of fetal VM together with karyotyping, especially in fetuses with bilateral VM and NIVM with abnormal CNS findings. Further study is necessary to explore the relationships between genotypes and phenotypes to facilitate prenatal diagnosis of fetal VM. © 2020 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Fetal ventriculomegaly Prenatal diagnosis Chromosomal microarray analysis Copy number variants Karyotype
1. Introduction Fetal ventriculomegaly (VM), defined as a lateral ventricle diameter of 10 mm, is a common cerebral abnormality detected during prenatal ultrasound screening [1], with reported incidence of 0.03e1% [1,2]. Fetal VM can be classified as mild (10e15 mm,
Abbreviations: VM, ventriculomegaly; CMA, chromosomal microarray analysis; CNV, copy number variant; CNS, central nervous system. * Corresponding author. Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, 1838 Guangzhou Avenue North, Guangzhou, 510515, Guangdong, China. E-mail address: [email protected] (Q. Chang).
MVM) or severe (15 mm, SVM) VM or hydrocephalus [1]; unilateral or bilateral VM; and isolated (only VM, IVM) or non-isolated VM (plus other ultrasonic abnormalities, NIVM) [2]. MVM has been suggested to increase the risk of neurodevelopmental disorders such as autism, epilepsy, and psychomotor disorders [3]. The etiology includes chromosomal or structural abnormalities and congenital infections [1]; however, the exact causes remain unknown. Chromosomal abnormalities occur in 5%e10.2% of fetuses with IVM and the incidence can increase to 18% in NIVM with other structural abnormalities, such as choroid plexus cysts and callosal agenesis [4,5]. Because of the diverse causes and prognosis of the different types of VM, genetic counseling and prenatal diagnosis of fetal VM
https://doi.org/10.1016/j.ejpn.2020.01.016 1090-3798/© 2020 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
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are challenging in clinical practice. Karyotyping remains the gold standard for detecting chromosomal abnormalities in fetal VM. However, it is limited in detecting abnormalities larger than 5 Mb and cannot identify copy number variants (CNVs) such as 16q12.1 deletion and 22q11.2 duplication [6,7], which are associated with fetal VM. Chromosomal microarray analysis (CMA), characterized by high-resolution and whole-genome, not only can identify numerical chromosomal abnormalities, as can karyotyping, but can also provide an additional diagnostic yield by revealing imbalances or submicroscopic CNVs at a kilobase level that are not detectable by routine karyotyping [8]. CMA has thus become the first-tier diagnostic tool for genetic evaluation of neurodevelopmental disorders, mental retardation, and spontaneous miscarriage [9e11]. The American College of Obstetricians and Gynecologists recommends prenatal diagnosis by CMA rather than karyotyping when fetuses show structural ultrasonic abnormalities [12]. Some studies have applied CMA for prenatal diagnosis of fetal central nervous system (CNS) abnormalities, including VM; however, the sample size for fetal VM was small or the focus was on anomalies other than VM, and results on the diagnostic yield of CMA and/or karyotyping for fetal VM were variable [6,7]. Therefore, in this retrospective study, we systematically investigated the distribution and further evaluated the detection rates of chromosome abnormalities or CNVs in fetuses with different types of VM by karyotyping and/or CMA to provide better prenatal counseling and perinatal management. 2. Methods 2.1. Subjects This study was performed in Nanfang Hospital affiliated to Southern Medical University. Between January 2014 and June 2019, 312 pregnancies with fetal VM, either with or without other structural anomalies, were referred for prenatal consulting and diagnosis at the Prenatal Diagnostic Center. The diagnosis of fetal VM was confirmed at our hospital. After the exclusion of twin pregnancies and failure of paracentesis or cell culture, 281 singleton fetuses with VM were included, who underwent prenatal diagnosis by karyotyping and/or CMA. All the subjects, aged 19e44 years, received prenatal consulting and provided written informed consent before the invasive procedure was performed. The median gestational age at the time of the procedure was 26.4 ± 4.0 weeks (range, 15þ6 to 37þ2). The results of prenatal diagnosis were recorded, and pregnancy outcomes were followed up. The study was approved by the ethics committee of Nanfang Hospital affiliated to Southern Medical University (NFEC-2017-035). 2.2. Ultrasonic examination Ultrasonic examination for fetal VM was conducted transabdominally with a 2.5e5.0-MHz probe (Version 730 Expert and E8; GE Medical Systems, Zipf, Austria) by experienced operators, with measurements recorded in the standard planes according to the International Society of Ultrasound in Obstetrics and Gynecology guidelines [13]. Fetal VM was defined as a uni- or bilateral lateral ventricle width 10 mm and was classified as MVM, SVM, or hydrocephalus; unilateral or bilateral VM; IVM or NIVM, as described [2,14]. 2.3. Sample collection According to the gestational week, amniotic fluid and umbilical blood samples were collected by ultrasound-guided transabdominal amniocentesis and cordocentesis, respectively. Thirty
milliliters of amniotic fluid or 3 mL of umbilical blood was extracted for karyotyping and CMA. Parental peripheral blood samples were collected to exclude maternal contamination and were used for auxiliary interpretation of the CNVs when necessary.
2.4. Karyotyping Karyotyping was conducted following standard protocols for cultured amniocytes or blood cells using standard G-banding [15]. At least 20 metaphase cells were counted, and five metaphase cells were examined to detect numerical and structural chromosomal abnormalities.
2.5. CMA and data analysis Fetal genomic DNA was extracted from cultured cells using the QIAamp DNA Mini Kit (Qiagen, Hilden, Germany). CMA was carried out using Infinium™ OmniZhongHua-8 v1.3 BeadChips (Illumina, Inc., San Diego, CA, USA). DNA amplification, hybridization, and analysis were carried out as per the manufacturer's instructions. Whole-genome BeadChip scan data were analyzed with KaryoStudio software and annotated to the reference genome GRCH37 (hg19). CNVs of unknown significance smaller than 500-kb deletion, 1-Mb duplication, or 10-Mb loss of heterozygosity (LOH) were not reported [16]. The clinical significance of the detected CNVs was interpreted based on information in databases and academic publications. The following databases were used: Database of Genomic Variants (DGV, http://dgv.tcag.ca/dgv/), International Standards for Cytogenomic Arrays (ISCA, http://www.iscaconsortium.org/), Online Mendelian Inheritance in Man (OMIM, http://www.ncbi.nlm.nih. gov/omim), Chromosomal Imbalance and Phenotype in Humans Using Ensemble Resources (DECIPHER, https://decipher.sanger.ac. uk/), University of California Santa Cruz Genomic Browser (UCSC, http://genome.ucsc.edu/), and PubMed (https://www.ncbi.nlm.nih. gov/pubmed/). Based on guidelines of the American College of Medical Genetics [17], the CNVs in this study were classified into pathogenic (P), benign (B), or variants of uncertain significance (VOUS/V). DNA extracted from parental peripheral blood samples was subjected to CMA to analyze whether the detected fetal CNVs were inherited or de novo.
2.6. Statistical analyses Data were analyzed using SPSS software (version 20.0, IBM, Armonk, NY, USA). Continuous variables are reported as the mean ± standard deviation (SD). Means were compared using Chisquare test, or Fisher's exact test. P-values < 0.05 were considered statistically significant.
3. Results The characteristics of the 281 singleton fetuses with VM are summarized in Table 1. The mean maternal age was 29.0 ± 5.0 years, and the mean gestational age was 26.4 ± 4.0 weeks. Fortyfive subjects (16.0%) had an advanced maternal age (35 years old). CMA was conducted in addition to karyotyping for 218 (77.6%) fetuses. The detection rate of chromosomal abnormalities by karyotyping was 12.1% (34/281), whereas it was 20.6% (58/281) when CMA was also conducted (c2 ¼ 7.486, P ¼ 0.006).
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
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3.2. Distribution of chromosomal abnormalities and detection rates in 218 cases by karyotyping and CMA
Table 1 Characteristics of 281 singleton fetuses with ventriculomegaly. Characteristic MA (years) <35 35 Mean Mean GA (weeks) at detection Parity Nulliparous Parous Method of sampling Amniocentesis (A) Umbilical blood sampling (U) Detection method Karyotyping only Karyotyping plus CMA Total detected positive rates Karyotyping Karyotyping plus CMA
n
n (%)
236 45 29.0 ± 5.0 26.4 ± 4.0
84.0% 16.0% e e
123 158
43.8% 56.2%
205 76
73.0% 27.0%
63 218
22.4% 77.6%
34 58
12.1% 20.6%
3
c2
P
7.486
0.006*
MA, maternal age; GA, gestational age; CMA, chromosomal microarray analysis; c2, Chi-square test value. *P < 0.05.
3.1. Chromosomal abnormalities and CNVs detected in fetuses with VM As shown in Table 2, 34 (12.1%) fetuses with VM were found to have chromosomal abnormalities by karyotyping, including 16 aneuploidies and 18 other abnormalities. Trisomy 21 was the most common aneuploidy (n ¼ 10), and trisomy 18, trisomy 13, 47, XXX, 47, XYY, and triploidy were also detected. Other abnormalities included 46, XN, inv (9) (p12q13), 46, X, inv(Y) (p11.2q11.2) and so on. In subgroup analysis, chromosomal abnormalities were significantly more abundant in bilateral fetal VM than in unilateral VM (20.5% versus 6.5%; P < 0.05). However, we observed no significant differences in chromosomal abnormalities between MVM and SVM, nor between IVM and NIVM (both P > 0.05). Chromosomal abnormalities were detected by CMA in 17.4% of cases (Table 3), including five aneuploidies and 33 CNVs; this detection rate was higher than that by karyotyping. In particular, pathogenic CNVs were identified in 11 out of 218 (5.0%) cases. Seventeen cases were found to have benign CNVs, and five cases had VOUS or LOH. No significant differences were found between MVM (17.8%) and SVM (10.0%), or between unilateral VM (13.5%) and bilateral VM (22.8%). However, the detection rate by CMA was significantly different between NIVM (21.4%) and IVM (10.3%) (P < 0.05). In general, CMA had a higher positive detection rate of chromosomal abnormalities than karyotyping for most VM types.
As shown in Table 4, the overall detection rate of chromosomal abnormalities in fetal VM by CMA was 17.4%, whereas that of karyotyping was 9.6% (P < 0.05). Notably, CNVs were detected by CMA in 23 fetuses with normal karyotypes, suggesting a 10.6% additional diagnostic value. As for the different VM types, detection rates were significantly different between karyotyping and CMA in the MVM, unilateral VM, and NIVM groups (all P < 0.05), with additional detection rates of 11.1e11.9%. In 140 fetuses with NIVM (Table 5), CMA showed a significantly higher detection rate than did karyotyping (21.4% versus 11.4%, P < 0.05). Fourteen (10.0%) pathogenic CNVs and aneuploidies were detected among 140 fetuses with NIVM, eight of whom exhibited CNS abnormalities, and 16 (11.4%) CNVs were benign or VOUS. In addition, CMA had significant benefits over karyotyping in cases of fetal VM with single-system abnormal ultrasound findings. Fetal VM was often detected in association with other abnormal ultrasound findings, mainly of the CNS (n ¼ 73), followed by the cardiovascular system (n ¼ 48), including dilatation of posterior fossa cistern, agenesis of the corpus callosum, and intracardiac echogenic foci. 3.3. CNVs detected by CMA in 23 fetuses with VM and pregnancy outcomes As shown in Table 6, 23 fetuses had normal karyotypes, but CNVs, including 14 duplications, eight deletions, and one LOH. Clinically significant pathogenic CNVs were identified in three fetuses, indicating a 1.4% (3/218) incremental yield by CMA; two of these fetuses had NIVM with CNS and CVS malformations, and one had unilateral IVM. All these pregnancies were terminated. Two pregnancies opted for TOP because of multiple fetal CNS malformations. LOH on chromosome 7q21.1 was detected in Case 31, with unclear clinical significance. The remaining 17 cases had benign CNVs or VOUS, and the mothers continued the pregnancy and had live births by delivery or cesarean section. 4. Discussion To systematically investigate the distribution and further evaluate the detection rates of chromosomal abnormalities or CNVs in fetuses with different types of VM by karyotyping and/or CMA, we conducted a retrospective study of 312 fetuses with VM. The results suggested that CMA effectively improved the detection rates in bilateral and NIVM with CNS abnormalities over karyotyping, with an additional diagnostic rate of 10.6% in fetuses with normal
Table 2 Distribution of chromosomal abnormalities in fetuses with ventriculomegaly detected by karyotyping (n ¼ 281). Karyotyping
Total
Mild
Severe
Unilateral
Bilateral
Isolated
Non-isolated
Number (%) Trisomy 21 Trisomy 18 Trisomy 13 47, XXX 47, XYY Triploidy Others Positive (n) P, rates (%)
281 10 1 2 1 1 1 18 34 12.1%
271 (96.4%) 9 1 2 1 1 1 17 32 11.8% 0.606 0.346
10 (3.6%) 1 0 0 0 0 0 1 2 20%
169 (60.1%) 1 1 1 1 1 1 5 11 6.5% 12.461 0.000*
112 (39.9%) 9 0 1 0 0 0 13 23 20.5%
99 (35.2%) 2 0 0 1 0 0 4 7 7.1% 3.653 0.057
182 (64.8%) 8 1 2 0 1 1 14 27 14.8%
c2 P *P < 0.05.
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
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Table 3 Distribution of chromosomal abnormalities in fetuses with ventriculomegaly detected by CMA (n ¼ 218). CMA
Total
Mild
Severe
Unilateral
Bilateral
Isolated
Non-isolated
Number (%) Trisomy 21 Trisomy 13 Deletion Duplication Pathogenic Benign VOUS/LOH Positive (n) P, rate (%)
218 4 1 19 19 11 17 5 38 17.4%
208 (95.4%) 3 1 19 19 11 17 5 37 17.8% 0.040 1.000
10 (4.6%) 1 0 0 0 0 0 0 1 10.0%
126 (57.8%) 0 0 6 10 4 9 4 17 13.5% 3.219 0.073
92 (42.2%) 4 1 13 9 7 8 1 21 22.8%
78 (35.8%) 1 0 3 4 1 4 2 8 10.3% 4.344 0.037*
140 (64.2%) 3 1 16 15 10 13 3 30 21.4%
c2 P
CMA, chromosomal microarray analysis; VOUS, variants of uncertain significance; LOH, loss of heterozygosity. *P < 0.05.
Table 4 Comparison of detection rates in fetal ventriculomegaly by karyotyping and CMA (n ¼ 218). Detection rates of chromosomal abnormalities Types
Mild Severe Unilateral Bilateral Isolated Non-isolated Total
N
208 10 126 92 78 140 218
Karyotyping
CMA
Added
n (%)
n (%)
n (%)
19(9.1) 2(20.0) 4(3.2) 17(18.5) 5(6.4) 16(11.4) 21(9.6)
37(17.8) 1(10.0) 17(13.5) 21(22.8) 8(10.3) 30(21.4) 38(17.4)
23(11.1) 0 15(11.9) 8(8.7) 7(9.0) 16(11.4) 23(10.6)
c2
P
6.686 0.373 8.744 0.531 0.755 5.098 5.665
0.010* 1.000 0.005* 0.466 0.385 0.024* 0.017*
CMA, chromosomal microarray analysis. *P < 0.05 (karyotyping vs. CMA).
karyotypes, and of 5.0% in fetuses with pathogenic CNVs. Several deletions or duplications found in fetal VM have been associated with neurodevelopmental disorders. VM is detected in 1% of fetuses during prenatal ultrasonography and reportedly is linked to cognitive, language, and behavioral dysfunctions in childhood [18]. A recent study suggested that mild IVM is related to an increased risk of neurodevelopmental disorders, including autism and schizophrenia, in children [3]. Adverse neurodevelopmental outcomes occur in 7.9% of fetuses with mild IVM, and the prevalence may increase to 38e90% in fetuses with
severe IVM or hydrocephalus [4,19]. However, the association between fetal VM and the risk of adverse neurodevelopmental outcomes is controversial as the overall incidence of neurodevelopmental adversities in the general population is similar, and thus, large-cohort prospective studies are needed. Chromosomal abnormality is a common cause of fetal VM, with an incidence of 5e8.3% [2]. Owing to the complex causes, comprehensive evaluation and prenatal diagnosis by karyotyping and CMA are highly recommended when fetal VM is identified [3]. An abnormal karyotype, most commonly, trisomy 21 [20], is detected in approximately 5% of fetuses with MVM, and in 6.8% of fetuses with SVM [21]. In this study, the total detection rate of chromosomal abnormalities by karyotyping was 12.1%, with incidence rates of 11.8% for MVM and 20.0% for SVM, which were higher than those reported in previous studies [20,21]. This might be explained by different cut-offs for VM, combination with other ultrasound findings, or the high risk of serological screening. Chromosomal abnormalities were more common in bilateral than in unilateral VM. However, there was no significant difference in the incidence of abnormal karyotypes regardless of the severity of fetal VM or the presence of other ultrasound findings. Given its high resolution in detecting CNVs, CMA has a significantly higher detection rate for chromosomal aberrations than routine karyotyping has [22]. In this study, CMA identified chromosomal abnormalities in 17.4% of cases (38/218), including CNVs in 33 (15.4%) cases of fetal VM, which was higher than the number found by karyotyping (12.4%, 34/281). The detection rate for total
Table 5 Chromosomal abnormalities and detection rates in fetuses with non-isolated ventriculomegaly. Karyotyping
US findings
N
Total Single system 2 systems CNS CVS Digestive system AF Urinary system Skeletal system NF Others
140 80 60 73 48 23 19 18 15 10 26
CMA
Positive n (%)
T21 T13
Others
Positive n%
P
B/V
16(11.4) 6(7.5) 10(16.7) 8(11.0) 8(16.7) 3(13.0) 2(10.5) 3(16.7) 7(46.7) 3(30.0) 6(23.1)
4 1 3 2 2 1 1 1 2 1 1
12 5 7 6 6 2 1 2 5 2 5
30(21.4) 15(18.75) 15(25.0) 18(24.7) 10(20.8) 5(21.7) 3(15.8) 5(27.8) 7(46.7) 4(40.0) 7(26.9)
14 5 9 8 6 3 2 3 5 2 5
16 10 6 10 4 2 1 2 2 2 2
Added n%
c2
P
16(11.4) 10(12.5) 6(10.0) 11(15.1) 3(6.3) 2(8.7) 1(5.3) 2(11.1) 1(6.7) 1(10.0) 2(7.7)
5.098 4.440 1.263 4.679 0.274 0.592 0.224 0.625 0.000 0.209 0.103
0.024* 0.035* 0.261 0.031* 0.601 0.699 1.000 0.891 1.000 1.000 0.749
Others include increased S/D ratio (n ¼ 6), facial anomaly (n ¼ 5), fetal growth restriction (n ¼ 5), persistent right umbilical vein (n ¼ 4), single umbilical artery (n ¼ 3), abnormal external genital morphology (n ¼ 2), hydrocele (n ¼ 1) and dilation of the intrahepatic segment of umbilical vein (n ¼ 1). US, ultrasound; AF, amniotic fluid; P, pathogenic (including aneuploidies); B, benign; V, VOUS; NF, nuchal fold; CNS, central nervous system; CVS, cardiovascular system; CMA: chromosomal microarray analysis. *P < 0.05 (karyotyping vs. CMA).
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
Q. Chang et al. / European Journal of Paediatric Neurology xxx (xxxx) xxx
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Table 6 CNVs detected by CMA and pregnancy outcomes in 23 fetuses with ventriculomegaly. Case GA 1 2 3 4 5 6 7 8 9 10 11
12 13 14 15 16
17 18 19 20 21 22
23
U/ CMA A
35þ5 U arr[hg19]18p11p11.23(7,024,998 e7,578,782) 3 25þ4 A arr[hg19]11p15.4(5,487,596 e5,69,0691) 1 24þ1 A arr[hg19]15q11.2(22,754,322 e23,222,284) 1 25 A arr[hg19]2p24.3(13,579,747 e14,334,195) 3 23þ6 A arr[hg19]2q13(110,863,908 e110,982,530) 3 24þ2 A arr[hg19]2p25.2p25.3(4,124,656 e4,641,479) 1 28þ5 U arr[hg19] 8p23.2(2,355,745 2,801,788) 3 29þ6 U arr[hg19]19p12(22,363,682 e23,195,094) 3 25þ2 A arr[hg19]7q11.1(61,074,194 e62,935,337) 3 33þ4 U arr[hg19]15q22.31q23(66,981,329 e68,050,777) 1 28þ4 U arr[hg19]11p12(40,966,294 e43,095,376) 1; arr[hg19] Xp22.2p22.13(16,950,577 e17,711,019) 3
Size
Type
Karyotyping Ultrasound findings
Outcome
553 kb
Duplication
Normal
CS
203 kb
Deletion
467 kb
Normal
Unilateral VM; Posterior fossa cistern widened; Dilation of the third ventricle Bilateral VM
CS
Deletion
Normal
Unilateral VM; Thickened nuchal fold
CS
736 kb
Duplication
Normal
Unilateral VM; Posterior fossa cistern cyst
CS
118 kb
Duplication
Normal
Unilateral VM; Choroid plexus cyst
CS
517 kb
Deletion
Normal
Delivery
446 kb
Duplication
Normal
Bilateral VM; Posterior fossa cistern cyst; Bilateral renal pelvis separation Bilateral VM; Ependymal cyst; Echogenic bowel; Bowel dilation
Delivery
831 kb
Duplication (paternal) Duplication
Normal
Unilateral VM
Delivery
Normal
Unilateral VM; Nasal bone dysplasia
Delivery
1.07 Mb
Bilateral VM; Ascending aorta dilation; S/D ratio increased
TOP
24þ4 A arr[hg19]10q26.3(134,987,109 e135,135,377,570) 3 30þ1 U arr[hg19]16p13.11p13.12(14,760,734 e16,303,388) 1 27þ3 A arr[hg19]7q11.23(72,305,671 e75,067,967) 3 37þ1 A arr[hg19]21q11.2(14,368,320 e15,696,202) 3 33þ1 U arr[hg19]2q12.2q12.3(106,878,354 e108,440,138) 3; arr[hg19] 6q21(111,673,714e112,732,041) 3 32þ3 A arr[hg19]17q24.1q25.3(62,781,579 e81,051,007) 3 33 U arr[hg19]19p13.3(2,888,242 e3,664,094) 1 23þ4 A arr[hg19]6q25.2(152,689,195 e153,226,106) 1 32þ3 A arr[hg19]15q11.1q11.2(20,161,372 e23,086,929) 3 24þ4 A arr[hg19]7q21.1(78,463,648 e92,558,612) 2hmz 24þ6 A arr[hg19]16p13.11(14,968,859 e16,291,983) 1
390 kb
Duplication
TOP Bilateral VM; Posterior fossa cistern cyst; Dilation of the fourth ventricle; Cavum vergae cyst; Cerebellum dysplasia; Cardiomegaly; Tricuspid regurgitation; Pulmonary valve stenosis with regurgitation; Foramen ovale dilation; Fetal growth restriction; Echogenic bowel Unilateral VM CS
1.54 Mb
Deletion Normal (pathogenic) Duplication Normal (pathogenic) Duplication Normal
Unilateral VM; Choroid plexus cyst; Cavum septum pellucidum cyst Unilateral VM
TOP
Bilateral VM
CS
1.56 M; 1.06 Mb
Duplication
Normal
Unilateral VM; Posterior fossa cistern widened; Polyhydramnios
CS
18.3 Mb
Duplication
Normal
TOP
775 kb
Normal Normal
Delivery
2.93 Mb
Deletion (VOUS) Deletion (VOUS) Duplication
Unilateral VM; Cerebellum dysplasia; Posterior fossa cistern widened; Arachnoid cyst; Unilateral VM; Posterior fossa cistern widened; Dilation of the third ventricle Unilateral VM
Normal
Bilateral VM; Left hydronephrosis with ureteral dilatation
Delivery
14.1 Mb
LOH (VOUS) Normal
CS
1.32 Mb
Normal
CS
31þ6 U arr[hg19]15q21.3q22.2(58,801,234 e60,474,270) 3
1.67 Mb
Deletion (VOUS) (parents' normal) Duplication (VOUS)
Unilateral VM; Cavum septum pellucidum disappeared and the anterior horn and body of the lateral ventricle fused Bilateral VM
Normal
Unilateral VM; Ventricular bright spot; Fetal growth restriction
CS
1.86 Mb
Deletion Normal (pathogenic) 2.13 Mb; Deletion; Normal 760 kb Duplication
2.76 Mb 1.33 Mb
536 kb
Normal
TOP
CS
This table does not include chromosome aneuploidy. GA, gestational age; A, amniocentesis; U, umbilical cord blood puncture; CMA, chromosomal microarray analysis; CS, caesarean section; TOP, termination of pregnancy; LOH, loss of heterozygosity; VOUS, variants of uncertain significance; S/D ratio, the ratio of fetal umbilical artery systolic blood pressure to diastolic blood pressure.
pathogenic CNVs in fetal VM was 5.0% (11/218), which was similar to the reported detection rate of 5.1% in mild to severe VM [23]. Several pathogenic CNVs, such as deletions of 21q22.11, 22q12.1q12.3, and 6q27, were identified, which have been reported in cases with MardeneWalker syndrome [24], agenesis of the corpus callosum [25], and structural brain abnormalities including hydrocephalus and cerebellar malformations [26], respectively. In the subgroup analysis, the increase in the diagnostic yield was significantly higher with CMA than with routine karyotyping for MVM, unilateral VM, and NIVM, ranging from 11.1% to 11.9%. Pathogenic CNVs were detected in 7.1% (10/140) fetuses with NIVM, which is higher than the rate (6.6%) reported previously [23]. CNS
abnormality was the most common additional structural finding, in line with a previous report [5]. Together, these results indicate that in general, CMA is preferable over karyotyping for the detection of abnormal genomic variants in fetal VM. In fetuses with normal karyotypes, CMA detects clinically significant CNVs in 1e6% of pregnancies [8]. Similarly, in our study, CMA had an additional diagnostic yield of 10.6% (23/218) in detecting abnormalities in fetal VM with normal karyotypes, 1.4% (3/218) cases of which had clinically significant CNVs (summarized below) reported to be associated with neurodevelopmental disorders. Case 10 was a fetus with a 1.07-Mb 15q22.31q23 deletion, with
Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016
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Q. Chang et al. / European Journal of Paediatric Neurology xxx (xxxx) xxx
bilateral NIVM, ascending aorta dilation, and increased S/D ratio on ultrasound. Deletion of 15q22.31 is reportedly associated with intellectual disability or developmental delay [9] and is considered to be pathogenic; therefore, the mother underwent elective TOP. Case 13 was a fetus with unilateral VM, choroid plexus cyst and cavum septum pellucidum cyst, and had a 1.54-MB 16p13.11p13.12 deletion. Deletion of 16p13.11 reportedly is associated with microcephaly, developmental delay, behavioral abnormalities, and impairments in social interaction [27], and is a genetic factor for epilepsy and other neurodevelopmental disorders [28]. A wide spectrum of other abnormalities, including autism, intellectual disability, and congenital anomalies such as cleft lip, facial dysmorphism, and even holoprosencephaly, have been reported as well [29]. Owing to the multiple abnormalities in CNS and the reported phenotypes, pregnancy was terminated in this case. Case 14, a fetus with unilateral VM had a 2.76-Mb duplication in chromosome 7q11.23. This duplication is significantly associated with autism and schizophrenia [30]. Intellectual disability, language delay, social anxiety, and behavioral difficulties have been reported in patients with 7q11.23 deletion [31]. Brain malformations, hydrocephalus, and craniofacial and cardiac abnormalities have been reported as well [31]. Though diagnosed as having unilateral IVM and a normal karyotype, TOP was opted for in this case due to the pathogenic CNV. CMA is a sensitive method for detecting whole-genome chromosomal abnormalities or CNVs in fetal VM, providing more information for prenatal consultation and selective birth [20]. However, CMA has its own limitations, such as the inability to detect balanced rearrangements or mosaicism [8]. Further, VOUS presents a challenge for genetic counseling and diagnosis [8]. Therefore, pre-test counseling is necessary to inform the parents on the benefits, limitations, and diagnostic scope of CMA over other prenatal methods. One limitation of this study was that not all fetuses with VM had undergone MRI examination for the final diagnosis of IVM or NIVM, which might affect the incidence of different types of fetal VM. MRI can detect an anomaly that is not identified on ultrasound in 10.0% of fetuses, which might influence the choice of TOP by the parents [32]. Moreover, this was a retrospective observational study and the follow-up time of fetuses was limited. However, through follow-up of the cases with CNVs but normal karyotypes after birth, we found that four (4/14, 28.6%) cases aged from one to five years old had certain language, motor, and mental retardation, including inability to speak fluently or unclear pronunciation and poor intelligence assessment results, when compared with children of the same age, which will help to explore clinical significance of CNVs. With longer follow-up time and more samples, more clinically significant phenotypes might be found in fetal VM with CNVs but normal karyotypes, so as to better explore the relationship between genetic etiology and clinical manifestations. 5. Conclusions Fetal VM is a common abnormal CNS finding on prenatal ultrasound. Chromosomal abnormalities and CNVs, some of which are related to neurodevelopmental disorders in infants or children, contribute to the etiology. Compared with conventional karyotyping, CMA improves the prenatal detection rates, with an additional detection rate of 10.6% in fetuses with normal karyotypes and 5.0% in fetuses with clinically pathogenic CNVs. CMA is highly recommended for prenatal diagnosis together with karyotyping in fetuses with VM, especially those with bilateral and NIVM combined with abnormal CNS findings. In the future, the relationship between genotypes and phenotypes needs to be explored so as to facilitate prenatal diagnosis of fetal VM.
Declaration of competing interest All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. There are no conflicts of interest to declare. Acknowledgements We thank all the participants involved in the study and our colleagues in the Prenatal Diagnosis Center and Department of Obstetrics and Gynecology. References [1] Society for Maternal-Fetal Medicine, N.S. Fox, A. Monteagudo, J.A. Kuller, S. Craigo, M.E. Norton, Mild fetal ventriculomegaly: diagnosis, evaluation, and management, Am. J. Obstet. Gynecol. 219 (2018), https://doi.org/10.1016/ j.ajog.2018.04.039. B2eB9. [2] T. Hannon, P.W. Tennant, J. Rankin, S.C. Robson, Epidemiology, natural history, progression, and postnatal outcome of severe fetal ventriculomegaly, Obstet. Gynecol. 120 (2012) 1345e1353, https://doi.org/10.1097/ aog.0b013e3182732b53. [3] E. Thorup, L.N. Jensen, G.S. Bak, et al., Neurodevelopmental disorder in children believed to have isolated mild ventriculomegaly prenatally, Ultrasound Obstet. Gynecol. 54 (2019) 182e189, https://doi.org/10.1002/uog.20111. [4] G. Pagani, B. Thilaganathan, F. Prefumo, Neurodevelopmental outcome in isolated mild fetal ventriculomegaly: systematic review and meta-analysis, Ultrasound Obstet. Gynecol. 44 (2014) 254e260, https://doi.org/10.1002/ uog.13364. [5] F. Sethna, P.W. Tennant, J. Rankin, C.R. S, Prevalence, natural history, and clinical outcome of mild to moderate ventriculomegaly, Obstet. Gynecol. 117 (2011) 867e876, https://doi.org/10.1097/AOG.0b013e3182117471. [6] M. Schumann, A. Hofmann, S.K. Krutzke, et al., Array-based molecular karyotyping in fetuses with isolated brain malformations identifies diseasecausing CNVs, J. Neurodev. Disord. 8 (2016) 11, https://doi.org/10.1186/ s11689-016-9144-y. [7] L. Sun, Q. Wu, S.W. Jiang, et al., Prenatal diagnosis of central nervous system anomalies by high-resolution chromosomal microarray analysis, BioMed Res. Int. 2015 (2015) 426379, https://doi.org/10.1155/2015/426379. [8] B. Levy, R. Wapner, Prenatal diagnosis by chromosomal microarray analysis, Fertil. Steril. 109 (2018) 201e212, https://doi.org/10.1016/ j.fertnstert.2018.01.005. [9] V. Peycheva, K. Kamenarova, N. Ivanova, et al., Chromosomal microarray analysis of Bulgarian patients with epilepsy and intellectual disability, Gene 667 (2018) 45e55, https://doi.org/10.1016/j.gene.2018.05.015. [10] S. Liu, L. Song, D.S. Cram, et al., Traditional karyotyping vs copy number variation sequencing for detection of chromosomal abnormalities associated with spontaneous miscarriage, Ultrasound Obstet. Gynecol. 46 (2015) 472e477, https://doi.org/10.1002/uog.14849. [11] T. Sahoo, N. Dzidic, M.N. Strecker, et al., Comprehensive genetic analysis of pregnancy loss by chromosomal microarrays: outcomes, benefits, and challenges, Genet. Med. 19 (2017) 83e89, https://doi.org/10.1038/gim.2016.69. [12] Committee Opinion No, 682 Summary: microarrays and next-generation sequencing technology: the use of advanced genetic diagnostic tools in obstetrics and gynecology, Obstet. Gynecol. 128 (2016) 1462e1463, https:// doi.org/10.1097/aog.0000000000001814. [13] International Society of Ultrasound in Obstetrics and Gynecology Education Committee, Sonographic examination of the fetal central nervous system: guidelines for performing the ‘basic examination’ and the ‘fetal neurosonogram’, Ultrasound Obstet. Gynecol. 29 (2007) 109e116, https://doi.org/ 10.1002/uog.3909. [14] B. Scelsa, M. Rustico, A. Righini, et al., Mild ventriculomegaly from fetal consultation to neurodevelopmental assessment: a single center experience and review of the literature, Eur. J. Paediatr. Neurol. 22 (2018) 919e928, https://doi.org/10.1002/uog.12403. [15] U. Francke, Clinical and molecular cytogenetics and gene mapping: principles and techniques, Southeast Asian J. Trop. Med. Publ. Health 26 (Suppl 1) (1995) 34e43. [16] C.M. Armour, S.D. Dougan, J.A. Brock, R. Chari, B.N. Chodirker, I. DeBie, J.A. Evans, W.T. Gibson, E. Kolomietz, T.N. Nelson, F. Tihy, M.A. Thomas, D.J. Stavropoulos, On-Behalf-Of the Canadian College of Medical Geneticists. Practice guideline: joint CCMG-SOGC recommendations for the use of chromosomal microarray analysis for prenatal diagnosis and assessment of fetal loss in Canada, J. Med. Genet. 55 (2018) 215e221, https://doi.org/10.1136/ jmedgenet-2017-105013. [17] H.M. Kearney, E.C. Thorland, K.K. Brown, F. Quintero-Rivera, S.T. South, Working Group of the American College of Medical Genetics Laboratory Quality Assurance Committee, American College of Medical Genetics standards and guidelines for interpretation and reporting of postnatal
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Please cite this article as: Q. Chang et al., Prenatal detection of chromosomal abnormalities and copy number variants in fetuses with ventriculomegaly, European Journal of Paediatric Neurology, https://doi.org/10.1016/j.ejpn.2020.01.016