Causes & Incidence of ALS

Diverse and Mystifying

No clear cause in over 90% of cases

In more than 9 out of 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.

• 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.

Genetic history in 5% of cases

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 revealed that a single gene defect could account for a portion of these familial cases.

Gene mutation in 1–2% of cases

Mutations in the gene for the enzymes superoxide dismutase 1 (SOD1) or copper zinc superoxide dismutase have been found in approximately 15–20% of the familial cases of ALS and approximately 1–2% of all cases of ALS involve this particular gene mutation.

Researching the causes of ALS

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

Learn about our research