TRIPLET REPEAT POLYMORPHISM AND FRAGILE-X-SYNDROME IN THE INDIAN CONTEXT

Mental retardation due to fragile X syndrome is one of the genetic dis orders caused by tripler repeat expansion, CGG repeat involved in this disease is known to exhibit polymorphism even among normal individual s. Here we describe the development of suitable probes for detection o f polymorphism in CGG repeat at FMR1 locus as well as the diagnosis of fragile X syndrome. Using these methods polymorphism at the FMR1 locu s has been examined in 161 individuals. Ninety eight patients with unc lassified mental retardation were examined, of whom 7 were found to ha ve the expanded (CGG) allele at the FMR1 locus, The hybridization patt ern for two patients has been presented as representative data.