Rechercher du syndrome de l'x fragile par hybridation moleculaire chez 29 familles de retard mental hereditaire

The diagnosis of the fragile X syndrome was based on the detection of the fragile site by cytogenetic analysis, which is not completely reliable. Since 1991, a new diagnosis test have been described which detect mutation in the FMR-1 gene responsible for the mental retardation and the various somatic signs. In the present study, we show by Southern Blot and hybridation that 3 from 29 families had fragile X syndrome. Three profiles have been identified: normal, premutation and full mutation. We propose the use of the molecular approach to detect systematically the fragile Xmutation in boys or girls with unexplained mental retardation and for prenatal diagnosis