Several HM-linked CACNA1A gain-of-function mutations also produce permanent cerebellar symptoms ranging from slowly progressive cerebellar ataxia and/or nystagmus (with cerebellar atrophy in some cases) [14,36,37] or permanent ataxia [38,39] to early-onset cerebellar signs consistent with congenital ataxia [40–44]. The gene discussed is CACNA1A; the disease is cerebellar ataxia.