Spinocerebellar ataxia type 17 in Indian patients: two rare cases of homozygous expansions

We screened a cohort of 181 patients with features of primary progressive ataxia and chorea for spinocerebellar ataxias 17 (SCA17) mutation after excluding other known SCAs, Huntington's disease (HD), dentatorubral-pallidoluysian atrophy (DRPLA), and non-genetic causes. This study included patients with known family history of SCA, those with sporadic onset and cases of uncertain family history. Two unrelated patients with Huntington's disease-like phenotype and cerebellar signs are described with homozygous expansions of 47 and 48 CAG/CAA repeats. A family member with early signs of ataxia was found to carry 37 and 48 repeats. There were fewer CAA interruptions in the repeat sequences of patients than in the controls. The normal repeat range in controls was 21-42, with 91% of the alleles located between 33 and 39 repeats. This is the first report of rare homozygous SCA17 mutation in Indian patients presenting with HD-like phenotype.