Moreover, KCND3 pathogenic variants may be responsible for a wider phenotypic spectrum than previously thought, including autosomal recessive early-onset sporadic cerebellar ataxia (Kurihara et al., 2018), childhood epileptic encephalopathy (Wang et al., 2019), Parkinsonism, and cognitive impairment (Huin et al., 2017). This evidence concerns the gene KCND3 and Cognitive impairment.