Test Details: SCA7 is an autosomal dominant ataxia which is distinguished from other SCAs by marked retinal pigmentary degeneration leading to visual loss and macular degeneration in addition to ataxia. In SCA7 there is a CAG trinucleotide repeat expansion in chromosome 3p14-p21.1 which results in abnormal Ataxin-7 protein. This expanded repeat size is highly variable and corresponds with variable severity of symptoms.