KCND3 and cerebellar ataxia: Several lines of evidence support the pathogenicity of this KCND3 variant: (i) this nonsynonymous variant in the KCND3 gene, whose missense variants are frequently linked to cerebellar ataxia, contributes to a low allele frequency (<0.0001) in the population database gnomAD (Table 1) (criterion PP2 in the ACMG guideline); (ii) prediction of deleterious or damaging effects by multiple in silico bioinformatics analyses (Table 1) (criterion PP3); and (iii) the patient’s presentation of specific neurological symptoms relevant to KCND3-mutation-related SCA19/22 (criterion PP4).