Age of the intronic GAA triplet repeat expansion mutation in Friedreich ataxia.

Friedreich ataxia (FRDA), the most frequently inherited ataxia, is due in the vast majority of cases to a large expansion of an intronic GAA repeat.
Using linkage disequilibrium analysis based on haplotype data of seven polymorphic markers close to the frataxin gene, the age of FRDA founding mutational event (s) is estimated to be at least 682 +/-203 generations (95% confidence interval  564-801 g), a dating which is consistent with little or no negative selection and provides further evidence for an ancient spread of a pre-mutation (at-risk alleles) in western Europe.. 
