Likewise, human FHM mutations T501M and R583Q (located at voltage sensor domains, S2 Fig), which are linked to progressive cerebellar ataxia (with cerebellar atrophy in the case of R583Q) [14], decrease voltage-threshold for channel activation by ~ 7–10 mV [14,60]. The gene discussed is CACNA1A; the disease is Progressive cerebellar ataxia.