Accurate determination of ataxin-2 polyglutamine expansion in patients with intermediate-range repeats

Abstract

Spinocerebellar ataxia, type 2 (SCA2), results from an expansion of a stretch of polyglutamine repeats within the coding sequence of the ataxin-2 gene (ATX2), localized to chromosome 12q23-24. Recent studies have widened the clinical phenotype, notably for individuals with repeats of intermediate size, from 32 to 35 glutamine residues. This narrow range necessitates precise determination of repeat size. Diagnostic laboratories most often perform direct genotyping of ATX2 from polymerase chain-amplified patient DNA with subsequent sizing utilizing slab gel polyacrylamide gel electrophoresis (PAGE) or capillary electrophoresis. Using cloning and sequencing methods, we have constructed a ladder..