ATP7A and cerebellar ataxia: Milder missense mutations in ATP7A generate occipital horn syndrome, which is characterized by ataxia, dysarthria, moderate hypotonia, and intellectual disability in addition to systemic phenotypes (Das et al., 1995, Kaler et al., 1994), and SMAX3, where spinomuscular atrophy occurs independently of cognitive defects (Kennerson et al., 2010, Takata et al., 2004).