The autosomal dominant spinocerebellar ataxias (SCAs) represent a growing and heterogeneous clinical phenotype with ongoing discovery of causative etiologies. Methods: The authors collected DNA and clinically characterized a three-generation Filipino family segregating a dominant ataxia. Following elimination of several known SCA loci, a genome-wide linkage study was undertaken with additional fine mapping of 19q13. Results: Clinical characterization of affected family members revealed cerebellar signs including gait ataxia, limb ataxia/dysmetria, titubation, hypotonia, dysarthria, and nystagmus. Linkage was found in a ~4 cM region of 19q13 bounded by markers D19S867 and D19S553, with a maximum LOD score of 3.89 at markers D19S904, D19S246, and D19S907. This region overlaps with, though markedly reduces the previously described SCA13 locus. Conclusion: An autosomal dominant cerebellar ataxia clinically distinguishable from SCA13 overlaps with the SCA13 locus on chromosome 19q13.3.
Compositions and methods for spinocerebellar ataxia