Pathogenic hemizygous variants in the gene encoding the copper transporter ATP7A cause an X-linked recessive spectrum of disorders with variable clinical presentations, including classic Menkes disease (MD, MIM #309400), occipital horn syndrome (OHS, MIM #304150), and ATP7A-related distal hereditary motor neuropathy (dHMN, MIM #300489) [1]. The gene discussed is ATP7A; the disease is occipital horn syndrome.