Localization of Friedreich ataxia phenotype with selective vitamin E deficiency to chromosome 8q by homozygosity mapping

Friedreich ataxia and ataxia with selective vitamin E deficiency (AVED) share very similar clinical phenotypes. We have mapped the AVED locus to proximal 8q with only three large consanguinous Tunisian families, representing to our knowledge the first use of homozygosity mapping for primary linkage analysis. Subsequently, three additional families showed linkage with the same markers. A maximum lod score of 17.9 was obtained at = 0 for the haplotype D8S260 D8S510, consisting of the two closest markers. With only 6 families, the AVED locus is therefore mapped precisely as illustrated by the lod 1 confidence interval of 2.4 cM on either side of D8S260 D8S510. Isolation of a yeast artificial chromosome contig >800 kilobases (kb) showed that D8S260 and D8S510 are less than 400 kb apart. © 1993 Nature Publishing Group.