Linkage investigations in two families with hereditary ataxia.

In two families with autosomal dominant olivopontocerebellar atrophy (type IV), 15 affected and 44 unaffected members were typed for 28 genetic markers, including HLA. The lod scores for a possible HLA linkage, plotted against recombination fractions from 0.01 to 0.4, were negative. No evidence emerged for the presence of the ataxia-locus within measurable distance of the HLA-loci on chromosome 6. No indications were obtained that the ataxia-gene is linked with one of the other marker-genes.