De Boulle, Kristel

de Graaff, Esther

Hendrickx, Jan

Oostra, Ben A.

Reyniers, Edwin

Van Den Bos, Feikje

Van Roy, Bernadette

Verkerk, Annemieke J.M.H.

Vits, Lieve

Willems, Patrick J.

Abstract: The vast majority of patients with fragile X syndrome show a folate-sensitive fragile site at Xq27.3 (FRAXA) at the cytogenetic level, and both amplification of the (CGG)n repeat and hypermethylation of the CpG island in the 5' fragile X gene (FMR-1) at the molecular level. We have studied the FMR-1 gene of a patient with the fragile X phenotype but without cytogenetic expression of FRAXA, a (CGG)n repeat of normal length and an unmethylated CpG island. We find a single point mutation in FMR-1 resulting in an Ile367Asn substitution. This de novo mutation is absent in the patient's family and in 130 control X chromosomes, suggesting that the mutation causes the clinical abnormalities. Our results suggest that mutations in FMR-1 are directly responsible for fragile X syndrome, irrespective of possible secondary effects caused by FRAXA

Institutional Repository Universiteit Antwerpen

A point mutation in the FMR-1 gene associated with fragile X mental retardation

A point mutation in the FMR-1 gene associated with fragile X mental retardation

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Institutional Repository Universiteit Antwerpen