 Menkes is a fatal genetic form of copper deficiency caused by mutations in a copper-transporting ATPase ATP7A. Pre-symptomatic diagnosis and therapy with copper injections is associated with improved overall survival and, based on their molecular defects, with vastly better neurological outcomes in some patients compared to the usual natural history. One purpose of this study is to further evaluate the relationship between specific molecular defects and clinical responses to early copper treatment in Menkes disease. In addition, we seek to study the influence of parenteral copper treatment in related genetic disorders, and in unexplained copper deficiency conditions, often associated with non-specific neurological abnormalities. 