Mutations in endosomal NHE6 (also known as SLC9A6) are associated with intellectual disability, postnatal microcephaly, absent speech, ataxia with progressive cerebellar atrophy, epilepsy, and neurologic regression (Christianson et al., 1999; Pescosolido et al., 2014). Here, SLC9A6 is linked to cerebellar ataxia.