- Email: [email protected]
Prenatal identification of a marker chromosome 16 by chromosome microdissection and reverse FISH
European Journal of Medical Genetics 49 (2006) 306–312 http://france.elsevier.com/direct/ejmg
Original article
Prenatal identification of a marker chromosome 16 by chromosome microdissection and reverse FISH Joke de Pater a, Carla Van der Sijs-Bos a, Mieke Prins a, Jan Derks b, Jozefa Albrechts c, John Engelen c,* b
a Department of Biomedical Genetics, University Medical Centre, Utrecht, The Netherlands Department of Obstetrics, Gynaecology and Neonatology, University Medical Centre, Utrecht, The Netherlands c Cytogenetics Unit, Research Institute Growth and Development, Department of Clinical Genetics, Academic Hospital, P.O. Box 5800, 6202 AZ, Maastricht, The Netherlands
Available online 19 January 2006
Abstract Prenatal cytogenetic analysis of cultured amniocytes was performed after an increased foetal nuchal translucency thickness was detected by ultrasound in week 17 of a pregnancy. Analysis of GTG-banded chromosomes showed a small marker chromosome in six of the 12 colonies analysed. The supernumerary abnormal chromosome appeared to be positive with DA/DAPI staining and C-banding. The parents’ karyotypes were normal. Using microFISH and FISH with band-specific probes, we found the marker appeared to be derived from chromosome region (16)(p13.1→q12.2). Accurate identification of the marker chromosome was important for prenatal counselling: the marker chromosome contained euchromatic sequences, the foetus was carrying mosaic trisomy 16, and based on the literature the prognosis for the foetus was unfavourable and the pregnancy was terminated. © 2006 Elsevier SAS. All rights reserved. Keywords: MicroFISH; Prenatal diagnosis; Marker chromosome 16; Trisomy (16)(p13.1→q12.2)
* Corresponding
author. Tel.: +31 43 387 7818; fax: +31 0 43 387 7901. E-mail address: [email protected] (J. Engelen).
1769-7212/$ - see front matter © 2006 Elsevier SAS. All rights reserved. doi:10.1016/j.ejmg.2005.12.006
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
307
1. Introduction A marker chromosome is a structurally abnormal chromosome in which no part can be identified by standard cytogenetic techniques. Constitutional marker chromosomes are found with a frequency of 0.4–2.0/1000 at amniocentesis [1–4] and 0.24–0.3/1000 in live born individuals [5,6]. De novo marker chromosomes (reviewed by Starke et al. [7] and Liehr et al. [8]) are often supernumerary and difficult to identify with conventional cytogenetic techniques. There is a great variation in chromosomal origin and most of these markers have a C-band positive centromere, although markers with a neocentromere are also quite frequently reported. In recent years several (molecular) cytogenetic methods have been developed and used for the identification of marker chromosomes. Whole chromosome painting (WCP-FISH), multicolour spectral karyotyping (SKY) [9] and centromere-specific multicolour FISH (cenM-FISH) [10] are nowadays used to determine the chromosomal origin of a marker chromosome; however, the chromosome region present in a marker chromosome is not elucidated with these methods. Furthermore, chromosomal comparative genomic hybridisation (CGH) [11] and array-based CGH [12] can be used for the characterisation of marker chromosomes. The advantage of these methods is that they disclose both the chromosomal origin and the chromosome region present in the marker chromosome. Characterisation of a marker chromosome present in low mosaicism, however, might be a problem when using these techniques. Another approach to characterise a marker chromosome is chromosome microdissection combined with FISH (microFISH) [13]. By using microFISH the region of origin of the chromosomal material present in a marker chromosome can be determined, and mosaicism creates no problem. When encountered at prenatal diagnosis, the presence of a marker chromosome presents a difficult problem for the referring clinician because of the lack of knowledge on the genetic content. Thus, it is usually difficult to inform the parents precisely about the long-term prognosis for the child. Here we present a foetus with an extra marker chromosome 16 that was characterised with chromosome microdissection and reverse FISH (microFISH). 2. Material and methods Chromosome analysis was performed according to standard procedures using the in situ technique. C-banding was performed as described by Salamanca and Armendares [14], and microFISH as described by Engelen et al. [15]. In short, five copies of the marker chromosome were dissected using glass micro-needles controlled by a micro-manipulator. The dissected chromosomes were amplified with DOP-PCR and PCR products were labelled by nick-translation with biotin-14-dATP. Subsequently, this probe was used for reverse painting on metaphase chromosomes of a normal control following the protocol of Guan et al. [16]. 3. Results GTG-banded amniocytes were analysed from four different culture flasks and revealed a male karyotype with a supernumerary marker chromosome in six out of 12 colonies. Normal cells and cells with the extra marker chromosome were found in all the culture flasks, showing that the aberration represents a true mosaicism. The marker chromosome was approximately half the size of a chromosome 22 and it was not a ring chromosome. Chromosome analyses of both parents, performed in cultured lymphocytes, showed normal karyotypes. The de novo
308
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
Fig. 1. GTG-banding showing the supernumerary marker chromosome 16.
supernumerary abnormal chromosome appeared to be positive with DA/DAPI staining and Cbanding, suggesting that the marker chromosome contained heterochromatin. MicroFISH showed the marker to be derived from chromosome 16, consisting of the centromeric region and part of the short and long chromosome arms. Thus, the foetus was carrying mosaic partial proximal trisomy 16p and 16q. The karyotype was mos 47,XY,+mar.ish der(16)(p13.1q12.2) [6]/46,XY [6] (Fig. 1). 4. Clinical report In a gravida 1, para 0, 39-year-old female referred for amniocentesis because of advanced maternal age an increased foetal nuchal translucency thickness was detected on ultrasound in week 17 of the pregnancy. The pregnancy was terminated in the 22nd week because of the aberrant karyotype of the foetus. Post-mortem examination revealed a male foetus with a small, flat nose and a broad nose bridge. Eyes, ears, mouth and palate were normal. The neck was broad. All body measurements were within normal limits for gestational age (weight: 544 g; length: 20 cm; head circumference: 21 cm; femur length: 4.0 cm; foot length: 4.2 cm). After termination of the pregnancy foetal tissue was not tested for confirmation of the results. 5. Discussion The phenotypical consequences of a de novo marker chromosome encountered at prenatal diagnosis remain difficult to assess because of the unknown genetic content and possible uniparental disomy (UPD) of the marker chromosome’s sister chromatids. Valuable molecular cytogenetic tools to determine the genetic origin of a marker chromosome and thus solving this problem in genetic counselling are WCP-FISH, SKY, cenM-FISH, CGH and microFISH. Trisomy rescue is one of the proposed mechanisms in the formation of marker chromosomes and UPD has been shown to occur in cases with marker chromosomes (reviewed by Kotzot [17]). This makes the assessment of the phenotypical consequences for the foetus even more difficult as three independent factors are involved. First, the effects of the partial trisomy on the foetus and the placenta, second, the possibility of an autosomal recessive disease due to reduction to
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
309
homozygosity and third, the effects of imprinted genes on the foetus. To solve this problem, microsatellite-analysis or methylation-specific PCR can be performed after the identification of the origin of a marker chromosome. Marker chromosomes derived from chromosome 16 are rare [7,18–30]. Nine postnatal patients have been reported and three of these cases demonstrated normal development during the first year of life [18–20], but no long-term follow-up is available unfortunately. Felbor et al. [21] reported on two sisters with a paternally derived marker chromosome and normal development at 20 years and 24 years of age. One case [22] concerned a maternally transmitted mosaic marker chromosome 16 that was ascertained in a child with microcephaly, severe mental retardation and minor facial anomalies although the mother was normal. Crolla et al. [23] reported on a de novo non-mosaic marker that was ascertained because of mild mental retardation together with a teenage onset psychotic illness. The remaining two postnatal cases, reported by Shanske et al. [24] were twins that showed simultaneous occurrence of a ring chromosome (1) and ring chromosome (16). Both children showed microcephaly, growth and developmental delays and mild dysmorphic facial features (Fig. 2). Seven pregnancies with a mosaic marker chromosome 16 have been reported in the literature and were terminated [7,25–30]. No phenotypical abnormalities were seen in the foetuses reported by Bartsch et al. [25], Hastings et al. [26] and Hengstschläger et al. [27]. The foetus reported by Aviv et al. [28] had a Dandy–Walker malformation detected on ultrasound. From three foetuses there was no follow-up information available after termination of the pregnancies [23,25,29]. Starke et al. [7] reported on a prenatally detected marker chromosome 16 that contained no euchromatic sequences. As ultrasound examination showed no abnormalities and UPD 16 was excluded, the pregnancy was continued and resulted in a child without clinical signs. The chromosomal variation in the marker chromosome 16 was considerable. If present, mosaicism ranged between 13% and 90%, some markers were DA/DAPI positive, and others negative, some were monocentric and others dicentric, and the size ranged from the size of chro-
Fig. 2. Reverse painting with the probe generated by chromosome microdissection of the aberrant chromosome 16 on to a metaphase from a healthy donor.
310
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
mosome 22 to minute. These patients’ reports were not sufficiently informative for genetic counselling of the parents in our case. Moreover, so far, it is not yet clear which regions of chromosome 16 are critical and have clinical consequences. We therefore studied literature reports of patients with a “pure” duplication of the proximal part of the short arm of chromosome 16 until band p13.1 [31–33] and the long arm of chromosome 16 until band q12.2 [34, 35], as seen in our case, to assess the life expectancy of the foetus. The patient described by Carasco Juan et al. [31] with a trisomy (16)(p11.2p12) was referred for tremor-like movements and ocular revulsions without loss of consciousness. Clinical examination revealed occipital flattening, round face, facial dysmorphisms, short neck, trucal hypotonia and moderate motor retardation. Engelen et al. [32] reported on a mother and daughter with trisomy (16) (p11.2p12.1) showing mild mental retardation and behavioural problems. Two patients reported by Finelli et al. [33] with a trisomy (16)(p11.2p12.2) both had autistic behaviour; this was the only clinical feature they shared. Patient 1 showed severe mental retardation and epilepsy at the age of 3 years and clinical re-examination at age 25 years revealed facial anomalies and autism, an ataxic gait and bilateral club feet. Patient 2 showed borderline cognitive impairment and behavioural problems. Verma et al. [34] described a phenotypically normal mother and daughter with autism and trisomy (16)(q12.1). Severe mental and growth retardation with behavioural problems was reported in the patient of Engelen et al. [35] with a trisomy (16)(q11.2q13). Based on this data, the parents decided to terminate the pregnancy. The presence of de novo supernumerary marker chromosomes found in prenatal diagnosis present a problem for genetic counselling. Time to investigate marker chromosomes is limited and the degree of mosaicism might influence the phenotype. Above all, data are sparse, especially long-term follow-up data, and more published cases are required. Acknowledgements We would like to thank Jackie Senior for help in preparing the manuscript. References 1 E.B. Hook, P.K. Cross, Extra structurally abnormal chromosomes (ESAC) detected in amniocentesis: frequency in approximately 75,000 prenatal cytogenetic diagnoses and association with maternal and paternal age, Am. J. Hum. Genet. 40 (1987) 83–101. 2 L.Y.F. Hsu, Prenatal diagnosis of chromosome abnormalities, in: A. Milunsky (Ed.), Genetic Disorders and the Foetus. Diagnosis, Prevention and Treatment, Plenum Press, New York, 1986, p. 115. 3 E.S. Sachs, J.O. Van Hemel, J.C. Den Hollander, M.G.J. Jahoda, Marker chromosomes in a series of 10000 prenatal diagnoses: cytogenetic and follow-up studies, Prenat. Diagn. 7 (1987) 81–89. 4 D. Warburton, De novo balanced chromosome rearrangements and extra marker chromosomes identified at prenatal diagnosis: clinical significance and distribution of breakpoints, Am. J. Hum. Genet. 49 (1991) 995–1013. 5 K.E. Buckton, G. Spowart, M.S. Newton, H.J. Evans, Forty four probands with an additional “marker” chromosome, Hum. Genet. 69 (1985) 353–370. 6 P.A. Jacobs, The role of chromosome abnormalities in reproductive failure, Reprod. Nutr. Dev. (Supp. 1) (1990) 63–74. 7 H. Starke, A. Nietzel, A. Weise, A. Heller, K. Mrasek, B. Belitz, C. Kelbova, M. Volleth, B. Albrecht, B. Mitulla, R. Trappe, I. Bartels, S. Adolph, A. Dufke, S. Singer, M. Stumm, R.D. Wegner, J. Seidel, A. Schmidt, A. Kuechler, I. Schreyer, U. Claussen, Von, F. Eggeling, T. Liehr, Small supernumerary marker chromosomes (SMCs): genotype-phenotype correlation and classification, Hum. Genet. 114 (2003) 510–567. 8 T. Liehr, U. Claussen, H. Starke, Small supernumerary marker chromosomes (sSMC) in humans, Cytogenet. Genome Res. 107 (2004) 22–67.
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
311
9 E. Schrok, S. Du Manoir, T. Veltman, B. Schoell, J. Wienberg, M.A. Ferguson-Smith, Y. Ning, D.H. Ledbetter, I. Bar-Am, D. Soenksen, Y. Garini, T. Ried, Multicolor spectral karyotyping of human chromosomes, Science 273 (1996) 494–497. 10 A. Nietzel, M. Rocchi, H. Starke, A. Heller, W. Fiedler, I. Wlodarska, I.F. Loncarevic, V. Beensen, U. Claussen, T. Liehr, A new multicolor FISH appraoch for the characterization of marker chromosomes: centromere-specific multicolor-FISH (cenM-FISH), Hum. Genet. 108 (2001) 199–204. 11 A. Kallioniemi, O.P. Kallioniemi, D. Sudar, D. Rutovitz, J.W. Gray, F. Waldman, D. Pinkel, Comparative genomic hydridization for molecular cytogenetic analysis of solid tumors, Science 258 (1992) 818–882. 12 S. Solinas-Toldo, S. Lampel, S. Stilgenbauer, J. Nickolenko, A. Benner, H. Dohner, T. Cremer, P. Lichter, Matrix-based comparative hybridization: biochips to screen for genomic imbalances, Genes Chrom, Cancer 20 (1997) 399–407. 13 P.S. Meltzer, X.Y. Guan, A. Burgess, J.M. Trent, Rapid generation of region specific probes by chromosome microdissection and their application, Nat. Genet. 1 (1992) 24–28. 14 F. Salamanca, S. Armendares, C-bands in human metaphase chromosomes treated by barium hydroxide, Ann. Genet. 17 (1974) 135–136. 15 J.J.M. Engelen, J.C.M. Albrechts, A.J.H. Hamers, J.P.M. Geraedts, A simple and efficient method for microdissection and microFISH, J. Med. Genet. 35 (1998) 265–268. 16 X.Y. Guan, C.B. Cargille, S.L. Anzick, F.H. Thompson, P.S. Meltzer, M.L. Bittner, et al., Chromosome microdissection identifies cryptic sites of DNA sequence amplification in human ovarian carcinoma, Cancer Res. 55 (1995) 3380–3385. 17 D. Kotzot, Review and meta-analysis of systematic searches for uniparental disomy (UPD) other than UPD, 15, Am. J. Med. Genet. 111 (2002) 366–375. 18 J.A. Crolla, N.R. Dennis, P.A. Jacobs, A non-isotopic in situ hybridisation study of the chromosomal origin of 15 supernumerary marker chromosomes in man, J. Med. Genet. 29 (1992) 699–703. 19 A. Paolini-Giacobino, M.A. Morris, S.P. Dahoun, Prenatal supernumerary r(16) chromosome characterized by multiprobe FISH with normal pregnancy outcome, Prenat. Diagn. 18 (1998) 751–752. 20 R. Sanz, M.A. Anabitarte, M.E. Querejeta, Rapid identification of a small dicentric supernumerary marker derived from chromosome 16 with a modified FISH technique on amniotic fluid, Prenat. Diagn. 20 (2000) 63–65. 21 U. Felbor, D. Rutschow, T. Haaf, M. Schmid, Centromeric association of chromosome 16- and 18-derived microchromosomes, Hum. Genet. 111 (2002) 16–25. 22 D.F. Callen, M.L. Ringenbergs, J.C.S. Fowler, C.J. Freemantle, A.E. Haan, Small marker chromosomes in man: origin from pericentric heterochromatine of chromosomes 1, 9 and 16, J. Med. Genet. 27 (1990) 155–159. 23 J.A. Crolla, F. Long, H. Rivera, N.R. Dennis, FISH and molecular study of autosomal supernumerary marker chromosomes excluding those derived from chromosome 15 and 22: results of 26 new cases, Am. J. Med. Genet. 75 (1998) 355–366. 24 A.L. Shanske, P. Dowling, R. Schmidt, B.J. White, B. Russell, A. Bogdanow, R.W. Marion, Simultaneous occurrence of two supernumerary autosomal ring chromosomes r(1) and r(16) in twins, J. Med. Genet. 36 (1999) 625– 628. 25 O. Bartsch, A. Loitzsch, P. Kozlowski, M.L. Mazauric, G. Hickmann, Forty-two supernumerary marker chromosomes (SMCs) in 43273 prenatal samples: chromosomal distribution, clinical findings, and UPD studies, Eur. J. Med. Genet. 1 (2005) 1–13. 26 R.J. Hastings, D.L. Nisbet, K. Waters, T. Spencer, L.S. Chitty, Prenatal detection of extra structurally abnormal chromosomes (ESAC’s): new cases and review of the literature, Prenat. Diagn. 19 (1999) 436–445. 27 M. Hengstschläger, D. Bettelheim, R. Drahonsky, J. Deutinger, G. Bernaschek, Prenatal diagnosis of a de novo supernumerary marker derived from chromosome 16, Prenat. Diagn. 21 (2001) 477–480. 28 H. Aviv, R. Wolf, E. Davis, R. Wallerstein, Foetus with a de novo supernumerary marker chromosome 16 and a Dandy-Walker malformation detected on ultrasound, Prenat. Diagn. 25 (2005) 612–618. 29 D.F. Callen, H.J. Eyre, M.L. Ringenbergs, C.J. Freemantle, P. Woodroffe, A.E. Haan, Chromosomal origin of small marker chromosomes in man: characterization by molecular genetics, Am. J. Hum. Genet. 48 (1991) 769– 782. 30 J.A. Crolla, S.A. Youings, S. Ennis, P.A. Jacobs, Supernumerary marker chromosomes in man: parental origin, mosaicism and maternal age revisited, Eur. J. Hum. Genet. 13 (2005) 154–160. 31 J.L. Carasco Juan, J.C. Cigudosa, A. Otero Gómez, M.T. Acosta Almeida, J.L. García Miranda, De novo trisomy 16p, Am. J. Med. Genet. 68 (1997) 219–221. 32 J.J.M. Engelen, C.E.M. de Die-Smulders, R. Dirckx, W.M.A. Verhoeven, S. Tuinier, L.M.G. Curfs, A.J.H. Hamers, Duplication of chromosome region (16)(p11.2→p12.1) in a mother and daughter with mild mental retardation, Am. J. Med. Genet. 109 (2002) 149–153.
312
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
33 P. Finelli, F. Natacci, M.T. Bonati, G. Gottardi, J.J.M. Engelen, C.E.M. De Die-Smulders, M. Sala, D. Giardino, L. Larizza, FISH characterisation of an identical (16)(p11.2p12.2) tandem duplication in two unrelated patients with autistic behaviour, J. Med. Genet. 41 (2004) E90. 34 R.S. Verma, S.M. Kleyman, R.A. Conte, Variant euchromatic band within 16q21.1, Clin. Genet. 52 (1997) 446– 447. 35 J.J.M. Engelen, C.E.M. de Die-Smulders, P.T.H. Vos, L.E.C. Meers, J.C.M. Albrechts, A.J.H. Hamers, Characterisation of a partial trisomie 16q with FISH. Report of a patient and review of the literature, Ann. Genet. 42 (1999) 101–104.
Original article
Prenatal identification of a marker chromosome 16 by chromosome microdissection and reverse FISH Joke de Pater a, Carla Van der Sijs-Bos a, Mieke Prins a, Jan Derks b, Jozefa Albrechts c, John Engelen c,* b
a Department of Biomedical Genetics, University Medical Centre, Utrecht, The Netherlands Department of Obstetrics, Gynaecology and Neonatology, University Medical Centre, Utrecht, The Netherlands c Cytogenetics Unit, Research Institute Growth and Development, Department of Clinical Genetics, Academic Hospital, P.O. Box 5800, 6202 AZ, Maastricht, The Netherlands
Available online 19 January 2006
Abstract Prenatal cytogenetic analysis of cultured amniocytes was performed after an increased foetal nuchal translucency thickness was detected by ultrasound in week 17 of a pregnancy. Analysis of GTG-banded chromosomes showed a small marker chromosome in six of the 12 colonies analysed. The supernumerary abnormal chromosome appeared to be positive with DA/DAPI staining and C-banding. The parents’ karyotypes were normal. Using microFISH and FISH with band-specific probes, we found the marker appeared to be derived from chromosome region (16)(p13.1→q12.2). Accurate identification of the marker chromosome was important for prenatal counselling: the marker chromosome contained euchromatic sequences, the foetus was carrying mosaic trisomy 16, and based on the literature the prognosis for the foetus was unfavourable and the pregnancy was terminated. © 2006 Elsevier SAS. All rights reserved. Keywords: MicroFISH; Prenatal diagnosis; Marker chromosome 16; Trisomy (16)(p13.1→q12.2)
* Corresponding
author. Tel.: +31 43 387 7818; fax: +31 0 43 387 7901. E-mail address: [email protected] (J. Engelen).
1769-7212/$ - see front matter © 2006 Elsevier SAS. All rights reserved. doi:10.1016/j.ejmg.2005.12.006
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
307
1. Introduction A marker chromosome is a structurally abnormal chromosome in which no part can be identified by standard cytogenetic techniques. Constitutional marker chromosomes are found with a frequency of 0.4–2.0/1000 at amniocentesis [1–4] and 0.24–0.3/1000 in live born individuals [5,6]. De novo marker chromosomes (reviewed by Starke et al. [7] and Liehr et al. [8]) are often supernumerary and difficult to identify with conventional cytogenetic techniques. There is a great variation in chromosomal origin and most of these markers have a C-band positive centromere, although markers with a neocentromere are also quite frequently reported. In recent years several (molecular) cytogenetic methods have been developed and used for the identification of marker chromosomes. Whole chromosome painting (WCP-FISH), multicolour spectral karyotyping (SKY) [9] and centromere-specific multicolour FISH (cenM-FISH) [10] are nowadays used to determine the chromosomal origin of a marker chromosome; however, the chromosome region present in a marker chromosome is not elucidated with these methods. Furthermore, chromosomal comparative genomic hybridisation (CGH) [11] and array-based CGH [12] can be used for the characterisation of marker chromosomes. The advantage of these methods is that they disclose both the chromosomal origin and the chromosome region present in the marker chromosome. Characterisation of a marker chromosome present in low mosaicism, however, might be a problem when using these techniques. Another approach to characterise a marker chromosome is chromosome microdissection combined with FISH (microFISH) [13]. By using microFISH the region of origin of the chromosomal material present in a marker chromosome can be determined, and mosaicism creates no problem. When encountered at prenatal diagnosis, the presence of a marker chromosome presents a difficult problem for the referring clinician because of the lack of knowledge on the genetic content. Thus, it is usually difficult to inform the parents precisely about the long-term prognosis for the child. Here we present a foetus with an extra marker chromosome 16 that was characterised with chromosome microdissection and reverse FISH (microFISH). 2. Material and methods Chromosome analysis was performed according to standard procedures using the in situ technique. C-banding was performed as described by Salamanca and Armendares [14], and microFISH as described by Engelen et al. [15]. In short, five copies of the marker chromosome were dissected using glass micro-needles controlled by a micro-manipulator. The dissected chromosomes were amplified with DOP-PCR and PCR products were labelled by nick-translation with biotin-14-dATP. Subsequently, this probe was used for reverse painting on metaphase chromosomes of a normal control following the protocol of Guan et al. [16]. 3. Results GTG-banded amniocytes were analysed from four different culture flasks and revealed a male karyotype with a supernumerary marker chromosome in six out of 12 colonies. Normal cells and cells with the extra marker chromosome were found in all the culture flasks, showing that the aberration represents a true mosaicism. The marker chromosome was approximately half the size of a chromosome 22 and it was not a ring chromosome. Chromosome analyses of both parents, performed in cultured lymphocytes, showed normal karyotypes. The de novo
308
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
Fig. 1. GTG-banding showing the supernumerary marker chromosome 16.
supernumerary abnormal chromosome appeared to be positive with DA/DAPI staining and Cbanding, suggesting that the marker chromosome contained heterochromatin. MicroFISH showed the marker to be derived from chromosome 16, consisting of the centromeric region and part of the short and long chromosome arms. Thus, the foetus was carrying mosaic partial proximal trisomy 16p and 16q. The karyotype was mos 47,XY,+mar.ish der(16)(p13.1q12.2) [6]/46,XY [6] (Fig. 1). 4. Clinical report In a gravida 1, para 0, 39-year-old female referred for amniocentesis because of advanced maternal age an increased foetal nuchal translucency thickness was detected on ultrasound in week 17 of the pregnancy. The pregnancy was terminated in the 22nd week because of the aberrant karyotype of the foetus. Post-mortem examination revealed a male foetus with a small, flat nose and a broad nose bridge. Eyes, ears, mouth and palate were normal. The neck was broad. All body measurements were within normal limits for gestational age (weight: 544 g; length: 20 cm; head circumference: 21 cm; femur length: 4.0 cm; foot length: 4.2 cm). After termination of the pregnancy foetal tissue was not tested for confirmation of the results. 5. Discussion The phenotypical consequences of a de novo marker chromosome encountered at prenatal diagnosis remain difficult to assess because of the unknown genetic content and possible uniparental disomy (UPD) of the marker chromosome’s sister chromatids. Valuable molecular cytogenetic tools to determine the genetic origin of a marker chromosome and thus solving this problem in genetic counselling are WCP-FISH, SKY, cenM-FISH, CGH and microFISH. Trisomy rescue is one of the proposed mechanisms in the formation of marker chromosomes and UPD has been shown to occur in cases with marker chromosomes (reviewed by Kotzot [17]). This makes the assessment of the phenotypical consequences for the foetus even more difficult as three independent factors are involved. First, the effects of the partial trisomy on the foetus and the placenta, second, the possibility of an autosomal recessive disease due to reduction to
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
309
homozygosity and third, the effects of imprinted genes on the foetus. To solve this problem, microsatellite-analysis or methylation-specific PCR can be performed after the identification of the origin of a marker chromosome. Marker chromosomes derived from chromosome 16 are rare [7,18–30]. Nine postnatal patients have been reported and three of these cases demonstrated normal development during the first year of life [18–20], but no long-term follow-up is available unfortunately. Felbor et al. [21] reported on two sisters with a paternally derived marker chromosome and normal development at 20 years and 24 years of age. One case [22] concerned a maternally transmitted mosaic marker chromosome 16 that was ascertained in a child with microcephaly, severe mental retardation and minor facial anomalies although the mother was normal. Crolla et al. [23] reported on a de novo non-mosaic marker that was ascertained because of mild mental retardation together with a teenage onset psychotic illness. The remaining two postnatal cases, reported by Shanske et al. [24] were twins that showed simultaneous occurrence of a ring chromosome (1) and ring chromosome (16). Both children showed microcephaly, growth and developmental delays and mild dysmorphic facial features (Fig. 2). Seven pregnancies with a mosaic marker chromosome 16 have been reported in the literature and were terminated [7,25–30]. No phenotypical abnormalities were seen in the foetuses reported by Bartsch et al. [25], Hastings et al. [26] and Hengstschläger et al. [27]. The foetus reported by Aviv et al. [28] had a Dandy–Walker malformation detected on ultrasound. From three foetuses there was no follow-up information available after termination of the pregnancies [23,25,29]. Starke et al. [7] reported on a prenatally detected marker chromosome 16 that contained no euchromatic sequences. As ultrasound examination showed no abnormalities and UPD 16 was excluded, the pregnancy was continued and resulted in a child without clinical signs. The chromosomal variation in the marker chromosome 16 was considerable. If present, mosaicism ranged between 13% and 90%, some markers were DA/DAPI positive, and others negative, some were monocentric and others dicentric, and the size ranged from the size of chro-
Fig. 2. Reverse painting with the probe generated by chromosome microdissection of the aberrant chromosome 16 on to a metaphase from a healthy donor.
310
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
mosome 22 to minute. These patients’ reports were not sufficiently informative for genetic counselling of the parents in our case. Moreover, so far, it is not yet clear which regions of chromosome 16 are critical and have clinical consequences. We therefore studied literature reports of patients with a “pure” duplication of the proximal part of the short arm of chromosome 16 until band p13.1 [31–33] and the long arm of chromosome 16 until band q12.2 [34, 35], as seen in our case, to assess the life expectancy of the foetus. The patient described by Carasco Juan et al. [31] with a trisomy (16)(p11.2p12) was referred for tremor-like movements and ocular revulsions without loss of consciousness. Clinical examination revealed occipital flattening, round face, facial dysmorphisms, short neck, trucal hypotonia and moderate motor retardation. Engelen et al. [32] reported on a mother and daughter with trisomy (16) (p11.2p12.1) showing mild mental retardation and behavioural problems. Two patients reported by Finelli et al. [33] with a trisomy (16)(p11.2p12.2) both had autistic behaviour; this was the only clinical feature they shared. Patient 1 showed severe mental retardation and epilepsy at the age of 3 years and clinical re-examination at age 25 years revealed facial anomalies and autism, an ataxic gait and bilateral club feet. Patient 2 showed borderline cognitive impairment and behavioural problems. Verma et al. [34] described a phenotypically normal mother and daughter with autism and trisomy (16)(q12.1). Severe mental and growth retardation with behavioural problems was reported in the patient of Engelen et al. [35] with a trisomy (16)(q11.2q13). Based on this data, the parents decided to terminate the pregnancy. The presence of de novo supernumerary marker chromosomes found in prenatal diagnosis present a problem for genetic counselling. Time to investigate marker chromosomes is limited and the degree of mosaicism might influence the phenotype. Above all, data are sparse, especially long-term follow-up data, and more published cases are required. Acknowledgements We would like to thank Jackie Senior for help in preparing the manuscript. References 1 E.B. Hook, P.K. Cross, Extra structurally abnormal chromosomes (ESAC) detected in amniocentesis: frequency in approximately 75,000 prenatal cytogenetic diagnoses and association with maternal and paternal age, Am. J. Hum. Genet. 40 (1987) 83–101. 2 L.Y.F. Hsu, Prenatal diagnosis of chromosome abnormalities, in: A. Milunsky (Ed.), Genetic Disorders and the Foetus. Diagnosis, Prevention and Treatment, Plenum Press, New York, 1986, p. 115. 3 E.S. Sachs, J.O. Van Hemel, J.C. Den Hollander, M.G.J. Jahoda, Marker chromosomes in a series of 10000 prenatal diagnoses: cytogenetic and follow-up studies, Prenat. Diagn. 7 (1987) 81–89. 4 D. Warburton, De novo balanced chromosome rearrangements and extra marker chromosomes identified at prenatal diagnosis: clinical significance and distribution of breakpoints, Am. J. Hum. Genet. 49 (1991) 995–1013. 5 K.E. Buckton, G. Spowart, M.S. Newton, H.J. Evans, Forty four probands with an additional “marker” chromosome, Hum. Genet. 69 (1985) 353–370. 6 P.A. Jacobs, The role of chromosome abnormalities in reproductive failure, Reprod. Nutr. Dev. (Supp. 1) (1990) 63–74. 7 H. Starke, A. Nietzel, A. Weise, A. Heller, K. Mrasek, B. Belitz, C. Kelbova, M. Volleth, B. Albrecht, B. Mitulla, R. Trappe, I. Bartels, S. Adolph, A. Dufke, S. Singer, M. Stumm, R.D. Wegner, J. Seidel, A. Schmidt, A. Kuechler, I. Schreyer, U. Claussen, Von, F. Eggeling, T. Liehr, Small supernumerary marker chromosomes (SMCs): genotype-phenotype correlation and classification, Hum. Genet. 114 (2003) 510–567. 8 T. Liehr, U. Claussen, H. Starke, Small supernumerary marker chromosomes (sSMC) in humans, Cytogenet. Genome Res. 107 (2004) 22–67.
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
311
9 E. Schrok, S. Du Manoir, T. Veltman, B. Schoell, J. Wienberg, M.A. Ferguson-Smith, Y. Ning, D.H. Ledbetter, I. Bar-Am, D. Soenksen, Y. Garini, T. Ried, Multicolor spectral karyotyping of human chromosomes, Science 273 (1996) 494–497. 10 A. Nietzel, M. Rocchi, H. Starke, A. Heller, W. Fiedler, I. Wlodarska, I.F. Loncarevic, V. Beensen, U. Claussen, T. Liehr, A new multicolor FISH appraoch for the characterization of marker chromosomes: centromere-specific multicolor-FISH (cenM-FISH), Hum. Genet. 108 (2001) 199–204. 11 A. Kallioniemi, O.P. Kallioniemi, D. Sudar, D. Rutovitz, J.W. Gray, F. Waldman, D. Pinkel, Comparative genomic hydridization for molecular cytogenetic analysis of solid tumors, Science 258 (1992) 818–882. 12 S. Solinas-Toldo, S. Lampel, S. Stilgenbauer, J. Nickolenko, A. Benner, H. Dohner, T. Cremer, P. Lichter, Matrix-based comparative hybridization: biochips to screen for genomic imbalances, Genes Chrom, Cancer 20 (1997) 399–407. 13 P.S. Meltzer, X.Y. Guan, A. Burgess, J.M. Trent, Rapid generation of region specific probes by chromosome microdissection and their application, Nat. Genet. 1 (1992) 24–28. 14 F. Salamanca, S. Armendares, C-bands in human metaphase chromosomes treated by barium hydroxide, Ann. Genet. 17 (1974) 135–136. 15 J.J.M. Engelen, J.C.M. Albrechts, A.J.H. Hamers, J.P.M. Geraedts, A simple and efficient method for microdissection and microFISH, J. Med. Genet. 35 (1998) 265–268. 16 X.Y. Guan, C.B. Cargille, S.L. Anzick, F.H. Thompson, P.S. Meltzer, M.L. Bittner, et al., Chromosome microdissection identifies cryptic sites of DNA sequence amplification in human ovarian carcinoma, Cancer Res. 55 (1995) 3380–3385. 17 D. Kotzot, Review and meta-analysis of systematic searches for uniparental disomy (UPD) other than UPD, 15, Am. J. Med. Genet. 111 (2002) 366–375. 18 J.A. Crolla, N.R. Dennis, P.A. Jacobs, A non-isotopic in situ hybridisation study of the chromosomal origin of 15 supernumerary marker chromosomes in man, J. Med. Genet. 29 (1992) 699–703. 19 A. Paolini-Giacobino, M.A. Morris, S.P. Dahoun, Prenatal supernumerary r(16) chromosome characterized by multiprobe FISH with normal pregnancy outcome, Prenat. Diagn. 18 (1998) 751–752. 20 R. Sanz, M.A. Anabitarte, M.E. Querejeta, Rapid identification of a small dicentric supernumerary marker derived from chromosome 16 with a modified FISH technique on amniotic fluid, Prenat. Diagn. 20 (2000) 63–65. 21 U. Felbor, D. Rutschow, T. Haaf, M. Schmid, Centromeric association of chromosome 16- and 18-derived microchromosomes, Hum. Genet. 111 (2002) 16–25. 22 D.F. Callen, M.L. Ringenbergs, J.C.S. Fowler, C.J. Freemantle, A.E. Haan, Small marker chromosomes in man: origin from pericentric heterochromatine of chromosomes 1, 9 and 16, J. Med. Genet. 27 (1990) 155–159. 23 J.A. Crolla, F. Long, H. Rivera, N.R. Dennis, FISH and molecular study of autosomal supernumerary marker chromosomes excluding those derived from chromosome 15 and 22: results of 26 new cases, Am. J. Med. Genet. 75 (1998) 355–366. 24 A.L. Shanske, P. Dowling, R. Schmidt, B.J. White, B. Russell, A. Bogdanow, R.W. Marion, Simultaneous occurrence of two supernumerary autosomal ring chromosomes r(1) and r(16) in twins, J. Med. Genet. 36 (1999) 625– 628. 25 O. Bartsch, A. Loitzsch, P. Kozlowski, M.L. Mazauric, G. Hickmann, Forty-two supernumerary marker chromosomes (SMCs) in 43273 prenatal samples: chromosomal distribution, clinical findings, and UPD studies, Eur. J. Med. Genet. 1 (2005) 1–13. 26 R.J. Hastings, D.L. Nisbet, K. Waters, T. Spencer, L.S. Chitty, Prenatal detection of extra structurally abnormal chromosomes (ESAC’s): new cases and review of the literature, Prenat. Diagn. 19 (1999) 436–445. 27 M. Hengstschläger, D. Bettelheim, R. Drahonsky, J. Deutinger, G. Bernaschek, Prenatal diagnosis of a de novo supernumerary marker derived from chromosome 16, Prenat. Diagn. 21 (2001) 477–480. 28 H. Aviv, R. Wolf, E. Davis, R. Wallerstein, Foetus with a de novo supernumerary marker chromosome 16 and a Dandy-Walker malformation detected on ultrasound, Prenat. Diagn. 25 (2005) 612–618. 29 D.F. Callen, H.J. Eyre, M.L. Ringenbergs, C.J. Freemantle, P. Woodroffe, A.E. Haan, Chromosomal origin of small marker chromosomes in man: characterization by molecular genetics, Am. J. Hum. Genet. 48 (1991) 769– 782. 30 J.A. Crolla, S.A. Youings, S. Ennis, P.A. Jacobs, Supernumerary marker chromosomes in man: parental origin, mosaicism and maternal age revisited, Eur. J. Hum. Genet. 13 (2005) 154–160. 31 J.L. Carasco Juan, J.C. Cigudosa, A. Otero Gómez, M.T. Acosta Almeida, J.L. García Miranda, De novo trisomy 16p, Am. J. Med. Genet. 68 (1997) 219–221. 32 J.J.M. Engelen, C.E.M. de Die-Smulders, R. Dirckx, W.M.A. Verhoeven, S. Tuinier, L.M.G. Curfs, A.J.H. Hamers, Duplication of chromosome region (16)(p11.2→p12.1) in a mother and daughter with mild mental retardation, Am. J. Med. Genet. 109 (2002) 149–153.
312
J. de Pater et al. / European Journal of Medical Genetics 49 (2006) 306–312
33 P. Finelli, F. Natacci, M.T. Bonati, G. Gottardi, J.J.M. Engelen, C.E.M. De Die-Smulders, M. Sala, D. Giardino, L. Larizza, FISH characterisation of an identical (16)(p11.2p12.2) tandem duplication in two unrelated patients with autistic behaviour, J. Med. Genet. 41 (2004) E90. 34 R.S. Verma, S.M. Kleyman, R.A. Conte, Variant euchromatic band within 16q21.1, Clin. Genet. 52 (1997) 446– 447. 35 J.J.M. Engelen, C.E.M. de Die-Smulders, P.T.H. Vos, L.E.C. Meers, J.C.M. Albrechts, A.J.H. Hamers, Characterisation of a partial trisomie 16q with FISH. Report of a patient and review of the literature, Ann. Genet. 42 (1999) 101–104.