Abstract
We report a mother and daughter with autosomal recessive ataxia with occulomotor apraxia in whom sequence analysis of senataxin revealed a dignosis of AOA2 (ataxia with occulomotor apraxia type 2) in both individuals. The apparent dominant inheritance pattern (pseudodominant) was the result of the unusual coincidence of both mother and daughter being compound heterozygotes for senataxin mutations. Our case exemplifies the challenges of diagnosis in hereditary ataxias, and the limitations of genetic testing guided solely by patterns of inheritance.