[A case pf spontaneous deletion in the FMR1 gene in a patient with the Martin-Bell syndrome].

The spontaneous deletion in FMR1 gene in a patient with the typical Fragile X phenotype was described. It was assumed that this deletion is located around CGG region in Pst1 fragment of the gene. The alleles with normal range of CGG copies and corresponding to premutation and full mutation ranges were revealed in mother-mosaic of proband. The possible mechanisms of trinucleotide repeat sequence instability are discussed.