Menkes syndrome: A genetic disorder that is characterized by fragile, twisted hair, growth delay, and progressive deterioration of the brain. Menkes syndrome is due to an error in copper transport that results in copper deficiency. The gene responsible for the syndrome is called ATP7A, on the X chromosome. Females are carriers of Menkes syndrome, and their sons who have the gene have the disease. If the disorder is recognized early, injections of copper have been sometimes beneficial. Also known as kinky hair syndrome and copper transport 'disease.