A patient presenting downbeat positioning nystagmus with 19/11 CAG repeats in the CACNA1A gene: A case report

Spinocerebellar ataxia type 6 (SCA6) is a polyglutamine disorder caused by the expansion of CAG repeats in the gene encoding voltage-gated calcium channel subunit alpha1 A (CACNA1A). The clinical features of SCA6 include slowly progressive cerebellar ataxia and downbeat positioning nystagmus. The clinical significance of 19 CAG repeats is unclear. We report a case with 19/11 CAG repeats in CACNA1A determined by direct sequencing. The case presented with DPN, which is one of the most important symptoms of SCA6, but did not present with ataxia.