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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

A rare and spontaneous syndrome

ALS is often referred to as a syndrome because the disease becomes apparent in various patterns. Currently, there is no cure for amyotrophic lateral sclerosis (ALS).

  • The incidence of ALS is five times higher than Huntington's disease and about equal to multiple sclerosis.
  • Most people who develop ALS are between the ages of 40 and 70, although the disease can occur at a younger age. Estimates suggest that ALS is responsible for as many as 5 of every 100,000 deaths in people aged 20 or older. ALS is most common among persons over age 60.
  • ALS occurs throughout the world with no racial, ethnic or socioeconomic boundaries.
  • Familial causes comprise only about 5% of ALS cases and the cause of the remaining sporadic cases is unknown.
  • Many ALS patients can live longer and more productive lives because of current research into the cause, prevention and cure for the disease. Improvements in medical management, including nutrition and breathing, regularly increase patient survival.
  • Today 50% of affected patients live at least three or more years after diagnosis, 20% live five years or more, and up to 10% will survive more than 10 years.

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Private donations help us continue provide comprehensive treatment while advancing therapies and working toward a cure for ALS. Learn more about ALS.

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