PREVALENCE OF THE FRAGILE X SYNDROME IN YUGOSLAV PATIENTS WITH NON-SPECIFIC MENTAL RETARDATION

Abstract

Mutations at two fragile sites, FRAXAand FRAXE, loci are caused by an expansion of a CGG/GCC trinucleotide repeat and are characterized by mental retardation. Here we report molecular screening survey of 97 unrelated individuals diagnosed with non-specific mental retardation (MR), which produced positive test for FRAXAin two boys and none positive for the FRAXEmutation. In addition, we studied allelic frequency distribution for the FRAXAlocus in this group of mentally retarded patients, as well as in the 99 healthy subjects of Yugoslav population. The distribution of FMR1CGG repeat size in both groups was similar: the most common allele contained 29 repeats (32.86% in the healthy population and 54.54% in MR population), followed by the allele with 28 CGG repeats (21.43% in the healthy and 12.2% in MR population). Premutation alleles with more than 45 repeats were not found in control nor in the MR group.