Loss-of-function mutations in ATP7A lead to Menkes disease (MD), a fatal, infantile-onset copper deficiency characterized by hypotonia, connective tissue defects, neurodegeneration, and failure to thrive.8 The severity of Menkes disease symptoms and overall survival is known to vary, even between related individuals with the same mutations in ATP7A. The gene discussed is ATP7A; the disease is Menkes disease.