Distinct distribution of autosomal dominant spinocerebellar ataxia in the Mexican population.

Dominant ataxias show wide geographic variation. We analyzed 108 dominant families and 123 sporadic ataxia patients from Mexico for mutations causing SCA1-3, 6-8, 10, 12, 17 and DRPLA. Only 18.5% of dominant families remained undiagnosed; SCA2 accounted for half (45.4%), followed by SCA10 (13.9%), SCA3 (12%), SCA7 (7.4%), and SCA17 (2.8%). None had SCA1, 6, 8, 12 or DRPLA. Among sporadic cases, 6 had SCA2 (4.9%), and 2 had SCA17 (1.6%). In the SCA2 patients we identified 6 individuals with the rare (CAG)(33) allele, 2 of whom showed early onset ataxia. The distribution of dominant ataxia mutations in Mexicans is distinct from other populations.