21q translocation in a patient previously reported as monosomy 21

European Journal of Medical Genetics 48 (2005) 167–174 www.elsevier.com/locate/ejmg

Original article

Unbalanced 18q/21q translocation in a patient previously reported as monosomy 21 M. Riegel a,*, P. Hargreaves a, A. Baumer a, M. Guc-Scekic b, M. Ignjatovic c, A. Schinzel a a

Institute of Medical Genetics of the University of Zurich, Schwerzenbach, Switzerland Laboratory of Medical Genetics, Mother and Child Health Institute “Dr.Vukan Cupic”, Belgrade, Yugoslavia c Department of Neonatology, Pediatric Clinic, Mother and Child Health Institute “Dr Vukan Cupic”, Belgrade, Yugoslavia b

Received 22 November 2004 Available online 01 February 2005

Abstract We describe a patient in whom full monosomy 21 was initially assumed from routine GTGbanded karyotyping. Re-examination with chromosome painting demonstrated an unbalanced translocation between the long arms of chromosomes 18 and 21. Fluorescence in situ hybridisation (FISH) and microsatellite marker analysis revealed partial monosomy of chromosome 21 (pter-q21) and 18(q22-qter). The patient, 18 years old at the second examination, revealed multiple dysmorphic features, genital hypoplasia, dilated cerebral ventricles, muscular hypotonia and severe mental retardation. In not one out of all patients investigated postnatally in whom an initial examination had revealed monosomy 21, this could be confirmed by FISH; in all of them, re-examination detected an unbalanced rearrangement leading to only partial monosomy 21 plus partial monosomy of another chromosome to which the distal 21q segment was attached. Thus, it is still highly likely that full monosomy 21 is incompatible with intra-uterine survival. © 2005 Elsevier SAS. All rights reserved. Keywords: Pseudo-monosomy 21; Deletion 18q22-qter; Deletion 21pter-q21; Unbalanced 18; 21 translocation

* Corresponding author. Institut für Medizinische Genetik, Universität Zürich, Schorenstr. 16, CH-8603, Schwerzenbach, Switzerland. Tel.: +41 1 655 7051; fax: +41 1 655 7220. E-mail address: [email protected] (M. Riegel). 1769-7212/$ - see front matter © 2005 Elsevier SAS. All rights reserved. doi:10.1016/j.ejmg.2005.01.026

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1. Introduction Over the years many cases of apparently full monosomy 21 by banded chromosome examination were re-examined applying fluorescence in situ hybridisation (FISH), and all were shown to have only partial monosomy of chromosome 21. In all reported cases the partial monosomy 21 resulted from unbalanced translocations leading to the deletion of centromeric segments of chromosome 21 and other autosomes involved [See,2,3]. So far, there is only one case in which full non-mosaic monosomy 21 was proven and demonstrated by chromosome painting and DNA polymorphism analysis in chorionic villi (confirmed in fetal fibroblasts) from a female fetus that died in utero at 14 weeks gestational age [4]. In this report, a propositus whose initial diagnosis was monosomy 21 by GTG banding techniques [1] was re-evaluated by FISH and microsatellite markers analysis. Painting with a chromosome 21 library and subtelomeric FISH revealed an unbalanced de novo translocation involving chromosomes 18q and 21q.

2. Clinical report The propositus, a boy, was born at 36 weeks of an uncomplicated pregnancy as the second child to a 27 year-old mother and 31 year-old father, both healthy and nonconsanguineous. Birth measurements: weight 3100 g (50–90th percentile), length 48 cm (50–90th percentile) and OFC 35 cm (>90th percentile). The patient was referred to the hospital at the age of 5 days. Clinical examination revealed a pattern of dysmorphic facial features: a large and prominent forehead, flat nose bridge, hypertelorism, downslanting palpebral fissures, inner epicanthic folds, bushy eyebrows with medial flaring, large mouth with prominent lips, and low set, posteriorly rotated ears with prominent upper helix and lobule, see Ref. [1]. The neck was mildly webbed. A mild systolic murmur was heard over the apex. The penis measured 2.3 cm in length (<10th percentile), and on palpation the cavernous body was underdeveloped. The right testis was not palpable in the scrotum. Bilateral transverse palmar creases, clinodactyly of the little fingers and equinovarus deformity of the feet were noticed. There was muscular hypotonia. Total body X-rays and electrocardiographic evaluation were normal. A cerebral CT scan showed minimal dilatation of the lateral cerebral ventricles. Complete blood count, blood glucose, urine analysis, amino acid studies of urine, as well as liver and thyroid function studies revealed normal results. The propositus was again hospitalized at the age of 13 months because of pneumonia. Generalized hypotonia was present: he was unable to stand and walk without support. Facial dysmorphic features were unchanged. No cardiac murmur was heard any more. The patient had regular controls, the last at the age of 18 years. At that time, his weight was 31.5 kg (<3rd percentile) and height 146.5 cm (<3rd percentile) (Fig. 1). Psychomotor development was severely delayed: he walked unassisted at age 20 years; toilet training had not yet been achieved. His language and motor skills corresponded to a 1–2 and 2–3 yearold, respectively. There was moderate bilateral hearing loss of undetermined type. Vision

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Fig. 1. Head of the propositus at age 18 years. For description see text.

was normal, and he never has had seizures. Puberty has had been delayed and diminished, but testicular size was normal for an adult. Reduced mobility was present in several joints with flexion deformities in most metacarpo-phalangeal and inter-phalangeal joints and feet asymmetric in form and size. 3. Cytogenetic, FISH and microsatellite marker investigations Chromosome analysis of the propositus and his parents was carried out on GTG-banded metaphases obtained from cultures of PHA-stimulated blood lymphocytes according to standard procedures. The FISH with a chromosome 21-specific library (Vysis, Inc., Downers Grove, IL, USA) and subtelomere probes (Vysis) for chromosomes 18p (D18S552,GDB:229270) and 18q (D181390,pVYS250E) and 21q (D21S1575, VIJ2RM2185,G31341) were performed on metaphases from the propositus according to the manufacturer’s instructions. Analysis was performed using a Zeiss Axioplan epifluorescence microscope, and images were recorded by Photometrics CCD KAF1400 camera (Photometrics, Tucson, AZ), controlled with Smart Capture imaging software (Vysis). Vysis imaging software was also used to convert the DAPI image into G-banded metaphases for identification of the chromosomes. DNA from the propositus and both parents was investigated with microsatellite markers mapping to the chromosomes of interest. Genomic DNA was extracted from peripheral blood from the propositus and his parents by standard methods. A number of microsatellite markers were analyzed covering the chromosome 21. The primer sequence information was obtained through the Genome Database (GDB) Linkage Maps for all used markers. Markers were purchased from Research Genetics (Huntsville, AL, USA). The precise localization of the markers was obtained through the National Center for Biotechnology Information (NCBI) and GDB. The microsatellite markers were used in polymerase chain reactions (PCR) and the products were separated on 6% denaturing polyacrylamide gels and visualized by silver staining using standard procedures.

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Fig. 2. Metaphase FISH analyses in the patient. (A) FISH with a chromosome 21-specific library showing a normal chromosome 21 (left) and a small segment of chromosome 21 attached distally to the long arm of chromosome 18 (right) and (B) FISH with subtelomere probes for chromosomes 18p (green) and 21q (red). Top normal 21 (red signal), bottom right normal 18 (green signal); bottom left translocation chromosome (green signal from 18p and red signal from 21q).

4. Results The initial karyotype of the propositus was reported as 45,XX,-21 in all 64 metaphases investigated, and complete non-mosaic monosomy 21 was assumed [1].The karyotypes of both parents were normal. Because of the unlikeliness that full monosomy 21 would exist in an adult, FISH examinations were carried out in order to exclude a hidden unbalanced translocation. Chromosome painting with a chromosome 21-specific library showed a signal on a normal chromosome 21 and painted a small segment on the long arm of an E-group chromosome suspected to be the chromosome 18 (Fig. 2A). Combination of the subtelomeric probes of 18p and 21q on metaphases from the patient confirmed that a segment of chromosome 21 had been translocated to 18q, with loss of the subtelomeric segment of 18q (Fig. 2B). Thus the case was re-classified as a de novo unbalanced translocation: 45,XX,-18,21,+der(18),t(18;21)(q22;q21) de novo. Microsatellite markers mapping to chromosome 21 and to the distal region of chromosome 18 were used in order to further investigate the deletion breakpoint and the parental origin of the deletion. Informative markers on chromosome 18 and on chromosome 21 showed that the deleted segments were derived from the father (Table 1). The breakpoint on chromosome 18 was found to be situated at 18q22.2-q22.3, and the breakpoint on chromosome 21 at 21q21.2-q21.3. 5. Discussion Initial chromosome examination of the propositus in 1983 revealed a 45,XY,-21 karyotype [1]. With the development of molecular cytogenetic techniques which allowed to correct the karyotypes in other cases published as “non-mosaic monosomy 21” (1q: [5]; 4p:

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Table 1 Summary of the results obtained for nine markers mapping to chromosome 18 and 8 markers mapping to chromosome 21. Alleles are given in the order mother (M)–patient (P)–father (F) Marker

Location

D18S62 D18S487 D18S64 D18S55 D18S61 D18S541 D18S43 D18S1661 D18S70

18p11.31 18q21.2 18q21.32 18q21.32 18q22.2 18q22.3 18q22.3 18q22.3 18q23

5816 kb 49,990 kb 55,575 kb 60,022 kb 65,585 kb 68,323 kb 68,949 kb 70,397 kb 75,963 kb

M aa ab ab cc bc bb bb bc cc

D21S11 D21S1905 D21S1437 D21S265 D21S263 D21S233 D21S219 D21S156

21q21.1 21q21.1 21q21.1 21q21.2 21q21.3 21q22.11 21q22.11 21q22.2

19,476 kb 19,867 kb 20,569 kb 25,841 kb 31,142 kb 32,162 kb 34,004 kb 39,256 kb

bc cd bb ab cd ab aa ac

Alleles P ab ab ab ac cd bb bb cc-

F Bb Ab Bb Ab Cc Ab Ab Ad Ab

Comments No deletion Not informative No deletion No deletion No deletion Not informative Not informative Paternal deletion Paternal deletion

bcbaad ab ab bc

Ad Ab aa cd ab ab ab bb

Paternal deletion Paternal deletion Paternal deletion Paternal deletion No deletion Not informative No deletion No deletion

[6–8]; 5p: [9–17]; 11q: [3,18]; 13q: [19–21] Xp: [13]; Xq: [22,23] it seemed likely that what appeared to be a pure monosomy 21 in fact was a hidden unbalanced translocation resulting in partial monosomy for centromere and proximal long arm only of chromosome 21 and partial monosomy of another autosome. Therefore, it was decided to re-investigate this patient with molecular methods in order to correct the karyotypic designation. The result was an unbalanced 18q;21q translocation leading to deletion of segments of about similar size of proximal 21q and distal 18q. The examinations in addition revealed that the rearrangement had occurred between the paternal chromosomes. So far, all patients previously reported as monosomy 21 and re-investigated by FISH turned out to have unbalanced translocations (see above) with the exception of a fetus who died in utero at about 15 weeks gestation with severe growth retardation, aniridia, Peter anomaly, aplasia of the retina, cleft palate, clubfeet and 3/4 syndactyly of fingers [4]. Occasionally, monosomy 21 is also found in early spontaneous abortions [24]. Other cases that could not be re-investigated by their characteristic clinical features most likely had deletions: of 4p [25], of 13q [26] and of 18p [27]. Some other patients with less distinct phenotypes were not re-investigated; it is, however, likely that a re-investigation would detect other unbalanced translocations ([28,29] (deletion of 4p?); [30] (deletion of 18p?); [31,32]). The unbalanced translocations giving rise to partial monosomy 21 involve different chromosomes with variable frequency. In 6 out of 13 reported cases the second chromosome involved in the translocation was a No. 5, resulting in the cri-du-chat phenotype. Thus the question arises whether there might be similar repeats at the two breakpoints (5p and 21q) enhancing recombinations. An attempt to delineate which of the propositus’ described in our paper features are due to the 18q and 21q deletion is difficult for the following reasons.

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The characteristic “18q-syndrome”, i.e., the distal 18q deletion is caused by a larger deletion than the one present in our patient, and the “pathognomonic segment” is assumed to be the distal 18q21 and proximal 18q22 bands which were not deleted in our proband [2]. Therefore, he did not show the characteristic midface hypoplasia, narrow external ear canals [33], and proximally placed thumbs. Prominent anthelices, another characteristic finding of the “18q-syndrome” was found, but is a rather non-specific sign. The proximal 21q deletion, however, by it’s nature practically always occurs in combination with aneuploidy of segments from other chromosomes, and hence it’s contribution—as well as a precise determination of the deleted segment—is in general difficult and/or was not elaborated. Chettouh et al. [34] based on a constructed molecular map of 23 manifestations seen in partial monosomy 21, concluded that deletion of chromosomal regions proximal to and including a major portion of band 21q21 does not seem to produce any significant phenotypic effect in partial monosomy 21q patients. Some clinical features of our patient such as growth retardation, multiple minor anomalies (antimongoloid position of the eyeaxes, low set ears, hypertelorism, epicanthic folds, depressed nasal bridge, genital hypoplasia, clinodactyly of little fingers, simian creases), and developmental delay with arthrogryposis-like joint contractures were found in most patients with del(21)(pter-q22.1) [2,18,35]. Hypertonia in the neonatal period is a consistent finding in patients with deletion of proximal 21q. In contrast, our patient presented generalized hypotonia during the first 13 months of life and afterwards developed hypertonia. The patients with del(18)(q21.3-qter) rarely have congenital malformations and thus survive relatively well. Unusual findings in single patients such as hiatus hernia [36], cardiomyopathy, ASD and hypothyroidism [37], APVR and hydronephrosis [36], and absent parathyroids [38] were not present in our patient. These findings suggest that partial monosomy of chromosome 21 has mainly contributed to determining the phenotype in our patient.

Acknowledgements The investigations were performed with the aid of the ECARUCA project of the European Council, project No. 03.0015.

References [1] [2] [3]

[4]

B. Garzicic, M. Guc-Scekic, G. Pilic-Radivojevic, M. Ignjatovic, N. Vilhar, A case of 21 monosomy, Ann. Genet. (Paris) 31 (1988) 247–249. A. Schinzel, Catalogue of Unbalanced Chromosome Aberrations in Man, second ed, Walter de Gruyter, Berlin and New York, 2001. M. Riegel, A. Baumer, A. Piram, D. Ortolan, L.C. Peres, J.M. Pina-Neto, De novo unbalanced t(11q;21q) leading to a partial monosomy 21pter-q22.2 and 11q24-qter in a patient initially diagnosed as monosomy 21, Genet. Couns. 12 (2001) 69–75. A.M.S. Joosten, S. de Vos, D. Van Opstal, H. Brandenburg, J.L.J. Gaillard, C.H. Vermeij-Keers, Full monosomy 21, prenatally diagnosed by fluorescent in situ hybridisation, Prenat. Diagn. 13 (1996) 271–275.

M. Riegel et al. / European Journal of Medical Genetics 48 (2005) 167–174 [5]

[6] [7]

[8] [9] [10] [11] [12]

[13]

[14] [15] [16] [17]

[18]

[19] [20] [21] [22] [23] [24]

[25] [26] [27] [28] [29]

173

W. Courtens, M.B. Petersen, J.C. Noel, J. Flament-Durand, N. Van Regemorter, D. Delneste, et al., Proximal deletion of chromosome 21 confirmed by in situ hybridization and molecular studies, Am. J. Med. Genet. 51 (1994) 260–265. J.G. Davis, E.C. Jenkins, H.P. Klinger, R.G. Weed, A child with presumptive monosomy 21 (45,XY,-21) in a family in which some members are Gq-, Cytogenet. Cell Genet. 17 (1976) 65–77. K. Wisniewski, M. Dambska, E.C. Jenkins, S. Sklower, W.T. Brown, Monosomy 21 syndrome: further delineation including clinical, neuropathological, cytogenetic and biochemical studies, Clin. Genet. 23 (1983) 102–110. X.L. Yao, E.C. Jenkins, Translocation 4p;21q identified by FISH in a case previously described as “presumptive monosomy 21”, Am. J. Med. Genet. 52 (1994) 491–492. M.C. Phelan, R.E. Stevenson, Monosomy of chromosome number 21, Proc. Greenwood Genet. Center 3 (1984) 26–29. A. Schinzel, Monosomy 21—an undetected translocation? Proc. Greenwood Genet. Center 4 (1985) 75. M.C. Phelan, Reply: monosomy 21—an undetected translocation, Proc. Greenwood Genet. Center 4 (1985) 76. M.C. Phelan, C.C. Morton, R.E. Stevenson, R.E. Tanzi, G.D. Stewart, P.C. Watkins, et al., Molecular and cytogenetic characterization of a de novo t(5p;21q) in a patient previously diagnosed as monosomy 21, Am. J. Hum. Genet. 43 (1988) 511–519. D.L. Viljoen, F. Speleman, R. Smart, N. Van Roy, J. Du Toit, J. Leroy, Putative monosomy 21 in two patients: clinical findings and investigation using fluorescence in situ hybridization, Clin. Genet. 42 (1992) 105–109. I. Lopez-Pajares, A. Martin-Ancel, P. Cabello, A. Delicado, A. Garcia-Alix, C. San Roman, De novo t(5p;21q) in a patient previously diagnosed as monosomy 21, Clin. Genet. 43 (1993) 94–97. P. Gill, S. Uhrich, C. Distèche, E. Cheng, Fetal t(5p;21q) misdiagnosed as monosomy 21: a plea for in situ hybridization studies, Am. J. Med. Genet. 52 (1994) 416–418. M.A. Iqbal, M.Z. Ahmed, D. Wu, N. Sakati, A case of presumptive monosomy 21 re-diagnosed as unbalanced t(5p;21q) by FISH and review of the literature, Am. J. Med. Genet. 70 (1997) 174–178. L. Flaherty, J. Moloney, N. Watson, L. Robson, L. Bousfield, A. Smith, A case of monosomy 21 found to be an unbalanced de novo t(5p;21q) by fluorescence in situ hybridization, J. Intellect. Diabil. Res. 42 (1998) 254–258. B. Hertz, C.A. Brabdt, M.B. Petersen, S. Pedersen, U. Konig, H. Stromkaer, et al., Application of molecular and cytogenetic techniques to the detection of a de novo unbalanced t (11q;21q) in a patient previously diagnosed as having monosomy 21, Clin. Genet. 44 (1993) 89–94. Y. Kaneko, T. Ikeuchi, M. Sasaki, Y. Satake, S. Kuwajima, A male infant with monosomy 21, Hum. Genet. 29 (1975) 1–7. A. Schinzel, Does full monosomy 21 exist? Hum. Genet. 32 (1976) 105–107. T. Ikeuchi, I. Kondo, M. Sasaki, Y. Kaneko, S. Kodama, Unbalanced 13q/21q translocation: a revised study of the case previously reported as 21-monosomy, Hum. Genet. 30 (1976) 327–330. K.H. Halloran, W.R. Breg, M.J. Mahoney, 21 monosomy in a retarded female infant, J. Med. Genet. 11 (1974) 386–389. B.R. West, E.F. Allen, Another previously described 21 monosomy case turns out to be an unbalanced translocation, Am. J. Med. Genet. 75 (1998) 438. T. Hassold, N. Chen, J. Funkhouser, T. Jooss, B. Manuel, J. Matsuura, A. Matsuyama, C. Wilson, J.A. Yamane, P. Jacobs, A cytogenetic study of 1000 spontaneous abortions, Ann. Hum. Genet. 44 (1980) 151–178. B. Hall, K. Fredga, N. Svenningsen, A case of monosomy G? Hereditas 57 (1967) 356–364. C.S. Houston, A.E. Chudley, Separating monosomy 21 from the “arthrogryposis basket”, J. Can. Assoc. Radiol. 32 (1981) 220–223. W.G.E. Cooksley, A. Firouz-Abadi, D.C. Wallace, Monosomy of a “G” autosome in a 22 year-old female, Med. J. Aust. 2 (1972) 178–180. P. Dziuba, D. Dziekanowska, H. Hubner, A female infant with monosomy 21, Hum. Genet. 31 (1976) 351–353. J.P. Fryns, F.D. D’Hondt, P. Goddeeris, H. Van den Berghe, in: Full monosomy 21: a clinically recognizable syndrome? Hum. Genet., 1977, pp. 155–159.

174

M. Riegel et al. / European Journal of Medical Genetics 48 (2005) 167–174

[30] U. Gripenberg, J. Elfving, L. Gripenberg, A 45,XX monosomy 21 child: attempt at a cytological and clinical interpretation of the karyotype, J. Med. Genet. 9 (1972) 110–115. [31] R. Herva, M. Koivisto, U. Seppänen, 21-monosomy in a liveborn infant, Eur. J. Pediatr. 140 (1983) 57–59. [32] M.C. Pellissier, N. Philip, M.A. Voelkel-Baeteman, M.G. Mattei, J.F. Mattei, Monosomy 21: a new case confirmed by in situ hybridization, Hum. Genet. 75 (1987) 95–96. [33] J.A. Veltman,Y. Jonkers, I. Nuijten, I. Janssen, W. Van der Vliet, E. Huys, J. Vermeesch, G. Van Buggenhout, J.P. Fryns, R. Admiraal, P. Terhal, D. Lacombe, A.G. Van Kessel, D. Smeets, E.F.P.M. Schoenmakers, C.M. Van Ravenswaaij-Arts, Definition of a critical region on chromosome 18 for congenital aural atresia by arrayCGH, Am. J. Hum. Genet. 72 (2003) 1578–1584. [34] Z. Chettouh, M.F. Croquette, B. Delobel, S. Gilgenkrantz, C. Leonard, C. Maunoury, et al., Molecular mapping of 21 features associated with partial monosomy 21: involvement of the APP-SODI region, Am. J. Hum. Genet. 57 (1995) 62–71. [35] K. Abe, H.X. Deng, N. Harada, K. Yoshiura, T. Oh-Hira, N. Niikawa, Monosomy for 21pter-q21:case report and assignment of a DNA clone (Fr8-77) to the deleted segment, Jpn. J. Hum. Genet. 35 (1990) 303–310. [36] P.D. Ghidoni, D.E. Hale, J.D. Cody, C.T. Gay, N.M. Thompson, E.B. McClure, et al., Growth hormone deficiency associated in the 18q deletion syndrome, Am. J. Med. Genet. 69 (1997) 7–12. [37] S. Cheema, L. Al-Nakib, T. Spencer, L. Butler, N. Sharief, Deletion of chromosome 18 with cardiomyopathy, Clin. Dysmorphol. 8 (1999) 227–228. [38] F. Greenberg, F.F.B. Elder, P. Haffner, H. Northrup, D.H. Ledbetter, Cytogenetic findings in a prospective series of patients with DiGeorge anomaly, Am. J. Hum. Genet. 43 (1988) 605–611.