Definition - a genetic disease in which loss of nerve cells in the spinal cord and
brainstem called motor neurons affects the part of the nervous system that controls voluntary muscle movement.

Cause - A genetic mutation that affects an X-chromosome gene for the androgen receptor protein, apparently making it toxic to nerve cells.

Onset - Adulthood - 30 to 50 years.

Symptoms - Weakness of the muscles of the mouth, throat, face and limbs. Symptoms related to abnormal processing of androgens (male hormones), such as breast enlargement and reduced fertility, may also occur.

Progression - Very slow (over decades)

Inheritance - X-linked recessive (Usually affects only men; - female carriers may have a mild form.)

Facts About Spinal Muscular Atrophy