Causes of ALS -- what we're looking for
As described here, ALS is a somewhat diverse and decidedly mystifying disease. In more than nine out of every 10 cases diagnosed, no clear identifying cause of the disease is apparent, that is, patients lack an obvious genetic history, complete with affected family members. Also, nothing about the way patients live their lives gives scientists and clinicians clues as to what causes ALS. Nothing in patients’ diet, where they’ve lived, how they’ve lived or what they’ve done with their lives can easily explain why they’ve developed this late onset, fully developed and progressive disease.

However, in about 5 percent of cases, a clear genetic history exists. The disease is classed as autosomal dominant in these patients; that is, that almost half of all family members show a clear history of ALS. Studies in the early 1990s on the genetic form of the disease, including work by one of our scientific advisors, Dr. Robert Brown, revealed that a single gene defect could account for a portion of these familial cases.

Mutations in the gene for the enzymes superoxide dismutase 1 (SOD1) or copper zinc superoxide dismutase have been found in approximately 15-20 percent of the familial cases of ALS. Some quick math shows, then, that approximately 1 to 2 percent of all cases of ALS involve this particular gene mutation.

Still, for the majority of ALS cases, we do not know what causes the disease. Researchers haven’t been idle, however, and several attractive theories exist on what could cause or contribute to the death of motor neurons in ALS. Center scientists are focusing on these pathogenic theories.