Cryptic 7Q21 and 9P23 Deletions in a Patient with Apparently
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J Hum Genet (2008) 53:876–885 DOI 10.1007/s10038-008-0321-z ORIGINAL ARTICLE Cryptic 7q21 and 9p23 deletions in a patient with apparently balanced de novo reciprocal translocation t(7;9)(q21;p23) associated with a dystonia-plus syndrome: paternal deletion of the epsilon-sarcoglycan (SGCE) gene C. Bonnet Æ M.-J. Gre´goire Æ M. Vibert Æ E. Raffo Æ B. Leheup Æ P. Jonveaux Received: 17 April 2008 / Accepted: 27 June 2008 / Published online: 24 July 2008 Ó The Japan Society of Human Genetics and Springer 2008 Abstract We report on a boy with myoclonus-dystonia PEG10 gene. Other genes in the deleted region on chro- (M-D), language delay, and malformative anomalies. mosome 7 are not imprinted. Nevertheless, a phenotype Genetic investigations allowed the identification of an can be due to haploinsufficiency of these genes. KRIT1 is apparently balanced de novo reciprocal translocation, implicated in familial forms of cerebral cavernous mal- t(7;9)(q21;p23). Breakpoint-region mapping using fluores- formations, and COL1A2 may be implicated in very mild cent in situ hybridization (FISH) analysis of bacterial forms of osteogenesis imperfecta. The deleted region on artificial chromosome (BAC) clone probes identified chromosome 9 overlaps with the candidate region for microdeletions of 3.7 and 5.2 Mb within 7q21 and 9p23 monosomy 9p syndrome. The proband shows dysmorphic breakpoint regions, respectively. Genotyping with micro- features compatible with monosomy 9p syndrome, without satellite markers showed that deletions originated from mental impairment. These results emphasize that the phe- paternal alleles. The deleted region on chromosome 7q21 notypic abnormalities of apparently balanced de novo includes a large imprinted gene cluster. SGCE and PEG10 translocations can be due to cryptic deletions and that the are two maternally imprinted genes. SGCE mutations are precise mapping of these aneusomies may improve clinical implicated in M-D. In our case, M-D is due to deletion of management. the paternal allele of the SGCE gene. PEG10 is strongly expressed in the placenta and is essential for embryo Keywords Translocation Á Deletion Á SGCE Á development. Prenatal growth retardation identified in the Myoclonus-dystonia patient may be due to deletion of the paternal allele of the Introduction C. Bonnet Á M.-J. Gre´goire Á P. Jonveaux (&) Nancy Universite´- EA 4002, Laboratoire de Ge´ne´tique, Centre Hospitalier Universitaire de Nancy-Brabois, Myoclonus-dystonia (M-D, DYT11, OMIM 159900) is a rue de Morvan, 54511 Vandoeuvre les Nancy, France dystonia plus syndrome. It begins in childhood or adoles- e-mail: [email protected] cence and is characterized by brief myoclonic muscle jerks frequently accompanied by mild dystonia affecting the M. Vibert Service de Pe´diatrie, Maternite´-Hoˆpital Sainte-Croix, arms, trunk, or bulbar muscles (Nardocci et al. 2008). Metz, France Optional diagnostic criteria are a positive response of symptoms to alcohol, and various personality disorders and E. Raffo psychiatric disturbances. Heterozygous loss-of-function Service de Me´decine Infantile I, Centre Hospitalier Universitaire de Nancy, mutations in the gene encoding SGCE, located on chromo- Vandoeuvre les Nancy, France some 7q21, have been identified in several cases (Zimprich et al. 2001). Most patients inherited the mutant allele from B. Leheup their father, suggesting a maternal imprinting (Muller et al. Service de Me´decine Infantile III et Ge´ne´tique Clinique, Centre Hospitalier Universitaire de Nancy, 2002; Grabowski et al. 2003). In general, large genomic Vandoeuvre les Nancy, France deletions are not as common as single-base alterations; 123 J Hum Genet (2008) 53:876–885 877 however, they contribute significantly to the proportion of was still present, with poor handwriting and more pro- human disease. Structural anomalies involving human nounced leg dystonia. Electroencephalogram (EEG) was chromosomes associated with abnormal phenotype are very unremarkable, and brain imaging, including scanner and informative because they may contribute to identify genes magnetic resonance imaging (MRI), was normal. Physical involved in the phenotype. In this study, we report on a boy examination revealed light skin color and a facial dysmor- with M-D and malformative anomalies associated with phism, including low eyebrows, anteverted nostrils, long apparently balanced de novo reciprocal translocation philtrum, and thick lower lip (Fig. 1a). between chromosomes 7 and 9. Breakpoint-region mapping allowed us to identify cryptic deletions, which could par- ticipate in the pathological phenotype through abnormal Materials and methods expression of dosage-sensitive genes. Cytogenetics and molecular cytogenetics Clinical report Blood samples from the patient and his parents were obtained after parental informed consent. Chromosome The patient was the first child of healthy parents without analysis was performed on peripheral blood lymphocytes family history. The pregnancy was spontaneous. Gesta- by means of GTG banding. Fluorescence in-situ hybrid- tional hypertension was diagnosed and treated from ization analysis (FISH) with whole-chromosome painting 14.5 weeks of gestation. Intrauterine growth retardation probes for chromosomes 7 and 9 (Vysis-Abbott, Des was initially diagnosed at 20 weeks. Ultrasound examina- Plaines, IL, USA) was performed on the patient’s meta- tion at 33.5 weeks demonstrated an increased heterogeneity phases. Other FISH experiments were conducted with of the placenta, with multiple hypoechogenic subchorial bacterial artificial chromosome (BAC) clones containing areas and confirmed growth retardation. At 36.5 weeks, chromosomes 7- or 9-specific sequences from several high placental vascular resistance was also reported. Birth locations (Table 1), in accordance with publicly available occurred at 38.5 weeks via Caesarean delivery, with birth genome resources [National Center for Biotechnology weight 2,390 g, length 47.5 cm, and head circumference Information (NCBI) Map Viewer : http://www.ncbi.nlm. 32.5 cm. Placental weight was 260 g, with a mean diameter nih.gov; Santa Cruz Human Genome Browser : http:// of 16 cm and mean thickness of 20 mm. Microscopic www.genome.ucsc.edu]. BAC probes were obtained from examination demonstrated a severe dystrophic pattern of the RPCI-1 and RPCI-11 libraries (BACPAC Resources the chorionic villi, with numerous terminal villi. Syncytio- Center, CHORI, Oakland, CA, USA) and selected trophoblast was by place retracted with clustered nuclei. according to their positions on chromosomes 7 or 9. BAC There was no abnormal fibrin plaque. Anal stenosis, phi- deoxyribonucleic acid (DNA) was labeled with biotin by mosis, and nonobstructive septal subaortic hypertrophy nick translation. The labeled probes were visualized with were observed soon after birth. Developmentally, the fluorescein isothiocyanate–avidin (Vector Laboratories, patient sat without support after the age of 9 months and Burlingame, CA, USA). walked at the age of 18 months. He was nonverbal until the age of 24 months. He was receiving speech and physical Molecular investigations therapy. Dystonic attitudes of the neck with lateral incli- nation of the head was first reported at the age of 1 year. Genotyping of the patient and his parents was performed Jerky movements of the neck, right shoulder, and right arm with ten chromosome 7 microsatellite markers: D7S657, appeared at 2 years. The jerks were seen in short, irregu- D7S652, D7S2430, D7S1820, D7S3050, COL1A2, ESG, larly repeated periods. Dystonic attitude of the right arm D7S2482, D7S2431, and D7S821, and three chromosome 9 was also present, largely accentuated by stress. The parents microsatellite markers: D9S759, D9S268, and D9S254 reported a decreased voluntary use of the right arm. The selected from the Genome Database (http://www.gdb.org). diagnosis of M-D syndrome was thereon proposed. Tri- Polymerase chain reaction (PCR) was performed using hexyphenidyl associated with diazepam treatment started at standard procedures with both locus specific primers. Each the age of 2 years 4 months did not fully control dystonia. reaction contained one fluorescently labeled primer. DNA Several episodes of dystonic attitude occurring several fragments were analyzed on an ABI Prism 310 Genetic times a month in the legs at night were also reported. Analyzer, and fragment sizes were determined with the Association of levodopa and benserazide started at age 4 GeneScan software (Applied Biosystems, Foster City, CA, accentuated the dystonia and was stopped. Spontaneous USA). disappearance of jerky movements was reported at age 6. At On quantitative multiplex PCR of short fluorescent the time of this report, at age 7 years, right arm dystonia fragments (QMPSF) analysis, short exonic fragments of the 123 878 J Hum Genet (2008) 53:876–885 Fig. 1 a Facial appearance of the patient at 1 year of age. b Facial encompassing SGCE and PEG10 genes showing one signal on appearance of the patient at 5 years of age. Written consent to publish normal chromosome 7 and absence of signal on der(7) (arrow). this photograph was obtained from the parents. c GTG-banded e FISH to metaphase using clone RP11-117J18 (12628464-12795950) chromosomes obtained from lymphocytes of the proband: karyotype showing one signal on normal chromosome 9 and absence of signal 46,XY,t(7;9)(q21;p23). d Fluorescent in situ hybridization (FISH) on der(9) (arrow) to metaphase using clone RP11-273O15 (934847754-94032828) 11 SGCE coding exons were simultaneously PCR ampli-