Abstract
Background: Williams-Beuren syndrome (WBS) is a rare multi-system genomic disorder, caused by 7q11.23 microdeletion with a prevalence of 1/7500 - 1/20,000 live births. Clinical phenotype includes typical facial dysmorphism (elfin face), mental retardation associated with a peculiar neuropsychological profile and congenital heart defects. Other signs are occasional like ocular, skeletal, renal and dental anomalies. Here in, we present 38 WBS Tunisian patients. Methods: All patients underwent a genetic consultation and in order to confirm the clinical diagnosis of WBS, fluorescent in situ hybridization (FISH) was applied on metaphase spreads using the dual color locus specific identifier WBS region probe (Vysis probe) that hybridized to the ELN and LIMK1 loci at 7q11.23 and to control loci D7S486 and D7S522 at 7q31. About 15 to 20 metaphases were analyzed for each case. Results: The mean age at diagnosis was 4 years and 4 months. All patients showed facial dysmorphism. 66% (23/35) have cardiovascular anomaly, peripheral pulmonary stenosis (10/35) is interestingly more frequent than the supravalvular aortic stenosis (7/35). Various degrees of mental retardation were present and a normal intelligence was found in three patients. The unique cognitive profile was found in all patients except one who had autistic disorders. Ocular anomalies (13/38) were less frequent than described, the skeletal anomalies too (12/38). Dental malformations were frequent (22/32). Idiopathic hypercalcemia was present in 50% of children less than one year (2/4). Conclusions: WBS was a rare disorder, cardinal signs (facial dysmorphism, mental retardation and cardiovascular defects) were found in our patients in the same proportions than described. The occasional clinical signs have proportion different of precedent reported like hypercalcemia, ocular and dental anomalies. The identification of the different clinical signs in WBS patients permits to establish a strategy of follow up.
Highlights
Williams-Beuren syndrome (WBS) is a rare multi-system genomic disorder, caused by 7q11.23 microdeletion with a prevalence of 1/7500 - 1/20,000 live births
The main clinical features are facial dysmorphism, mild to moderate mental retardation associated with a characteristic neuropsychological profile, congenital heart defects (most commonly supravalvar aortic stenosis (73%)) and growth retardation during the first two years of life
In order to confirm the clinical diagnosis of WBS, fluorescent in situ hybridization (FISH) was applied on metaphase spreads using the dual color locus specific identifier WBS region probe (Vysis probe) that hybridizes to the elastin gene (ELN) and LIMK1 loci at 7q11.23 and to control loci D7S486 and D7S522 at 7q31
Summary
Williams-Beuren syndrome (WBS) is a rare multi-system genomic disorder, caused by 7q11.23 microdeletion with a prevalence of 1/7500 - 1/20,000 live births. Williams-Beuren syndrome (WBS, OMIM #194050) is a multisystem disorder caused by hemizygous deletion of 1.5 to 1.8 Mb on chromosome 7q11.23, which contains approximately 28 genes [1]. About these genes, only the elastin gene (ELN) has been definitely associated with a specific feature of the phenotype, namely supravalvar aortic stenosis and systemic arterial anomalies [2]-[4]. The main clinical features are facial dysmorphism (elfin face), mild to moderate mental retardation associated with a characteristic neuropsychological profile, congenital heart defects (most commonly supravalvar aortic stenosis (73%)) and growth retardation during the first two years of life. Idiopathic infantile hypercalcemia is less frequent than initially thought and it generally resolves spontaneously [8] [9]
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