GENETIC-MAPPING OF THE SPINOCEREBELLAR ATAXIA-2 (SCA2) LOCUS ON CHROMOSOME-12Q23-Q24.1

A refined genetic map of the spinocerebellar ataxia 2 locus was constr ucted through linkage and haplotype analysis of 11 large pedigrees fro m the Holguin SCA2 family collective. Three-point analysis makes a loc alization of the SCA2 mutation in the 6-cM. interval D12S84-D12S79 lik ely. This is consistent with haplotype results indicating a crossover event between two branches of the SCA2 family Rs and placing the mutat ion on the telomeric side of D12S84. The microsatellite D12S105 within this interval shows a peak two-point lod score of Z = 16.14 at theta = 0.00 recombination and complete linkage disequilibrium among affecte d individuals. These data together with the observation of a common di sease haplotype among all family ancestors support the notion of an SC A2 founder effect in Holguin province. (C) 1995 Academic Press, Inc.