The increased ATP7A expression in the cerebellum may explain the increased sensitivity of this region, and in particular Purkinje neurons, to copper deficiency as observed in MD (Menkes et al., 1962; Kumode et al., 1993, 1994; Iwase et al., 1996; Geller et al., 1997; Liu et al., 2005a; Niciu et al., 2006). The gene discussed is ATP7A; the disease is Menkes disease.