[Molecular pathogenesis of fragile X syndrome].

The fragile X syndrome is an X-linked genetic disorder; manifesting primarily as intellectual disability. The disease is caused by the absence of functional FMRP, a protein encoded by the FMR1 gene. The expansion of trinucleotide repeats within the first exon of the gene contributes to most cases of the syndrome. This review summarizes the present knowledge of the relationship between the molecular defect in the FMR1 gene and the clinical phenotype associated with disease.