Exclusion of genetic linkage to the SPAX2 locus in cases of ataxia

Hereditary ataxias are neurodegenerative disorders that cause ataxia as a primary symptom, i.e., loss of coordination of voluntary movements, impaired sense of balance, and motor impairment. They form a clinically and genetically heterogeneous group. As a result, there are many classifications based on different criteria. However, the current consensus is that the mode of transmission is the primary criterion for classification. We recruited eight French-Canadian families from various regions of Quebec with a more or less close genetic link to Acadia, in which we observed ten cases of a relatively mild form of autosomal recessive spastic ataxia that resisted analysis of known ataxia genes. We hypothesized that we were dealing with a new form of ataxia with a founder effect for the French-Canadian population. In order to identify the mutated gene responsible for this ataxia, genomic screening of SNP markers for the recruited individuals was performed. Then, through homozygosity mapping, a 2.5 Mb region was identified on chromosome 17p13.