CHROMOSOMAL ASSIGNMENT OF THE 2ND LOCUS FOR AUTOSOMAL-DOMINANT CEREBELLAR-ATAXIA (SCA2) TO CHROMOSOME 12Q23-24.1

The autosomal dominant cerebellar ataxias (ADCA) are a group of neurod egenerative disorders characterized by onset with gait ataxia, dysarth ria, dysmetria and dysdiadochokinesia. We have demonstrated previously genetic heterogeneity within these disorders by excluding the disease locus from the documented spinocerebellar ataxia locus (SCA1) on chro mosome 6p in a large Cuban founder population. We now report the assig nment of a second locus for ADCA (SCA2) to chromosome 12q23-24.1 follo wing linkage analyses carried out for the Cuban pedigrees, with probab le flanking markers D12S58 and phospholipase A2. Investigation of link age to the interval containing SCA2 for seven French ADCA families, pr eviously excluded from linkage to SCA1, provides preliminary data sugg esting the existence of a third ADCA locus (SCA3).