Washington: Researchers have discovered two genetic mutations responsible for the third most common form of muscular dystrophy, paving way for new treatments for the disease.
Scientists led by Stephen Tapscott, from Fred Hutchinson Center`s Human Biology Division, found that a rare variant of Facioscapulohumeral muscular dystrophy (FSHD), called type 2, which accounts for about 5 per cent of cases, is caused by two genetic mutations.
These mutations together cause the production of muscle-damaging toxins responsible for causing this progressive muscle disease.
Researchers found that a combination of genetic variants on chromosomes 4 (called DUX4) and 18 (called SMCHD1) can cause type 2 FSHD.
The DUX4 variant was first described by the research team in 2010 as a mechanism behind the more common, type 1, version of the disease.
"Many diseases caused by a single gene mutation have been identified during the last several decades, but it has been more difficult to identify the genetic basis of diseases that are caused by the intersection of multiple genetic flaws," Tapscott said in a statement.
"Recent advances in DNA sequencing made this study possible and it is likely that other diseases caused by the inheritance of multiple genetic variants will be identified in the coming years," he said.
Understanding the genetic mechanisms of type 2 FSHD could lead to new biomarker-based tests for diagnosing the disease and could lead to the development of future treatments, Tapscott said.
FSHD affects about half a million people worldwide. Symptoms usually first appear around age 20 and are characterised by a progressive, gradual loss of muscle strength, particularly in the upper body.
The findings were published in the journal `Nature Genetics`.