Washington, Dec 6 (IANS): New research has thrown up evidence suggesting genetic mutations may contribute to more cases of amyotrophic lateral sclerosis (ALS) than scientists earlier believed.

ALS, also known as Lou Gehrig's disease, destroys the nerve cells that control muscles, leading to loss of mobility, difficulty in breathing and swallowing, and an eventual paralysis, and even death.

"To our surprise, we found that 26 percent of sporadic ALS patients had potential mutations in one of the known ALS genes we analysed," said Matthew Harms, assistant professor of neurology at Washington University.

"This suggests that mutations may be contributing to significantly more ALS cases." Harms added.

Alone or in combination, mutations in any of these genes can cause the disease in family members who inherit them.

Scientists had previously thought that mutations contributed to barely more than one in every 10 cases of sporadic ALS.

The scientists used a sequencing technique to look at 17 known ALS genes in the DNA of 391 patients with ALS.

Like the overall ALS patient population, 90 percent of the patients had no family history of disease.

It is not yet clear why some patients with sporadic ALS have mutations linked to the illness but no family history of the disorder.

"It is also possible that these mutations could be combining with environmental factors linked to ALS," said co-senior author Robert Baloh, associate professor of neurology at Cedars-Sinai Medical Center, Los Angeles.

The study showed having mutations in more than one ALS gene can accelerate the onset of symptoms.

The scientists are now analysing genetic data from additional patients with ALS to confirm their findings.

The study appeared online in the journal Annals of Neurology.