Their dysfunction results in well‐known genetic diseases of copper deficiency and overload, respectively: Menkes disease (MD) occurs when ATP7A is mutated, and Wilson disease (WD) when ATP7B is not functioning (La Fontaine and Mercer 2007; Gupta and Lutsenko 2009; LaFontaine et al. 2010. The gene discussed is ATP7B; the disease is Menkes disease.