Prevalence and clinical characteristics of fragile X syndrome at child development clinic, Ramathibodi Hospital.

Fragile X syndrome, the most common cause of inherited mental retardation, is an X-linked genetic disorder caused by an expanded CGG repeat in the fragile X mental retardation 1 gene. It is characterized by mental retardation, behavioral features, and physical features, such as a long face with large protruding ears and macro-orchidism. A screening for the syndrome was conducted in a representative sample of pediatric patients, who had developmental delay or mental retardation with unknown cause, at the Child Development Clinic, Ramathibodi Hospital. The DNA test was performed on all patients using PCR and southern blot techniques. Five positive cases were detected from 114 screened subjects, and more four cases confirmed among other family members. Two of five positive families initially denied a family history of mental retardation. Among 9 cases of fragile X syndrome, four had hyperactivity and two had autistic like behavior. More than half had rather a long face or prominent ears. Three boys had macro-orchidism.

Williams syndrome and the elastin gene in Thai patients.

Williams syndrome (WS) has long been known as a complex disorder of dysmorphic facial features, described as elfin face, mental retardation or learning disability, loquacious personality, and supravalvular aortic stenosis. The etiology is now known to be due to deletion of the elastin gene (ELN) on long arm of chromosome 7. Thai patients were previously reported by clinical diagnosis. This study reports the first two cases of WS with ELN deletion diagnosed by fluorescent in situ hybridization (FISH) technique. Clinically, hyperacusis is a common finding in WS associated with otitis media. Neither of the patients had hyperacusis, but one of them had bilateral sensorineural hearing loss, which to our knowledge, has never been reported.