Washington, Sept 21 : Scientists have discovered a common gene that causes both ALS (amyotrophic lateral sclerosis) and a form of early-onset dementia in a groundbreaking study led by US scientists.

In the study, scientists described the discovery of a genetic mutation that is accountable for almost 12 percent of familial frontotemporal dementia and more than 22 percent of familial ALS samples studied.

They also report that the defect is the strongest genetic risk factor found to date for the more common, non-inherited, sporadic forms of these diseases. It was found in 3 percent of sporadic FTD and 4 percent of sporadic ALS samples in the largest clinical patient series.

The study was led by scientists at the Mayo Clinic in Florida, in collaboration with researchers at UCSF, the University of British Columbia and UCLA. The finding emerged from the identification and study of a family stricken by both ALS and FTD, reported last year.

"Both clinically and at the molecular level this discovery is going to significantly improve our understanding of these diseases," said co-author Adam Boxer, MD, PhD, of the UCSF Memory and Aging Center, the lead author on the 2010 paper.

The discovery makes it possible to develop a diagnostic test for the mutation, as well as to create animal models that may be used to help unravel the molecular mysteries connecting the mutation to the diseases, he said.

The study was recently published in the journal Neuron. (ANI)