Observation of an excess of fragile-X premutations in a population of males referred with spinocerebellar ataxia.

Premutations of the fragile-X (FRAXA) gene were thought to have no clinical effects until recent reports of an increased incidence of premature ovarian failure in females and a late-onset neurological disorder in males. These patients were identified from families including typical fragile-X males with a full mutation. By analysing a cohort of patients with neurodegenerative disorders referred for genetic analysis of spinocerebellar ataxia genes, we have found that 3 of 59 males carry the premutation. Our patients extend the phenotype associated with the FRAXA premutation and indicate that it may account for a proportion of undiagnosed neurodegenerative disorders.