Methods to diagnostic FXS include molecular tests such as PCR that allows determining if there is a CGG expansion, which, in combination with SB, allows determining the exact number of CGG repeats and the degree of methylation of the FMR1 gene (10), and triplet-primed PCR assay that detects FMR1 alleles throughout the expanded range (11). This evidence concerns the gene FMR1 and fragile X syndrome.