Age at onset density distribution for dominant cerebellar ataxias. (A) Age at onset density distribution for dominant cerebellar ataxias due to mutations in channel genes (CACNA1A, CACNA1G, KCNC3, KCND3, KCNA1) (solid blue), mAAA-related ataxias (biallelic SPG7, monoallelic AFG3L2) (solid red), or SCA1, 2 and 3 (dotted green). (B) Age at onset density distribution for dominant cerebellar ataxias due to CACNA1A polyglutamine expansions (dotted green) versus point mutations (solid blue). Light dotted dark lines and grey background histograms show the age at onset distribution for all considered patients as a whole.