ATP7A-related distal motor neuropathy is a very rare genetic disorder that causes muscle weakness and a decrease in muscle tissue (atrophy) that gets worse with time (progressive). Symptoms can include weakness of both the arms and legs, really high or flat arch of the foot, and hand weakness. The disorder is caused by a change (mutation) in the ATP7A gene. This gene provides instructions for the body to make a protein involved in moving copper into and out of motor neurons (cells that carry signals from the brain to the muscles). When the ATP7A gene has a mutation, the level of copper in the motor neurons is abnormal, which causes the muscle weakness and atrophy. Individuals with this disease do not usually experience symptoms until they are adults and, although the disorder gets worse with time, it usually progresses slowly.
Males are at a higher risk than females to develop ATP7A-related distal motor neuropathy because the ATP7A gene is located on the X chromosome (inherited in an X-linked recessive manner). Males have only one X chromosome (one copy of the ATP7A gene) while females have two copies of the X chromosome (two copies of the ATP7A gene). If a male has a mutation in his only copy of the ATP7A gene, he will have ATP7A-related distal motor neuropathy. If a female has a mutation in one of her two copies of the ATP7A gene, she has another working copy and will usually not have symptoms of the condition. A diagnosis of ATP7A-related distal motor neuropathy is considered in a person who has muscle weakness and atrophy. Genetic testing is used to confirm the diagnosis. If you or a family member has been diagnosed with this disease, talk with your doctor about the current treatment options. Support groups are a good resource for additional infor