AUTOSOMAL-DOMINANT SPINOCEREBELLAR ATAXIA WITH SENSORY AXONAL NEUROPATHY (SCA4) - CLINICAL DESCRIPTION AND GENETIC LOCALIZATION TO CHROMOSOME 16Q22.1

The hereditary ataxias represent a clinically and genetically heteroge neous group of neurodegenerative disorders. Various classification sch emes based on clinical criteria are being replaced as molecular charac terization of the ataxias proceeds; so far, seven distinct autosomal d ominant hereditary ataxias have been genetically mapped in the human g enome. We report linkage to chromosome 16q22.1 for one of these genes (SCA4) in a five-generation family with an autosomal dominant, late-on set spinocerebellar ataxia; the gene is tightly linked to the microsat ellite marker D16S397 (LOD score = 5.93 at theta = .00). In addition, we present clinical and electrophysiological data regarding the distin ct and previously unreported phenotype consisting of ataxia with the i nvariant presence of a prominent axonal sensory neuropathy.