Cause of Amyotrophic Lateral Sclerosis (ALS)

There is no known cause for ALS.  Researchers have looked into theories including environmental exposure and a variety of infections and have not yet discovered the source for the disease. In 10% of patients with ALS there is a family history of the disease.  Approximately 20% of these familial cases of ALS have a specific gene, called Superoxide Dismutase 1 which is abnormal.  This gene can be tested for through a blood test. Otherwise there is no other specific genetic relationship for the majority of the cases of ALS.