Researchers discover 2 genetic flaws behind common form of inherited muscular dystrophy

November 11, 2012

SEATTLE - An international research team co-led by a scientist at Fred Hutchinson Cancer Research Center has identified two genetic factors behind the third most common form of muscular dystrophy. The findings, published online in Nature Genetics, represent the latest in the team's series of groundbreaking discoveries begun in 2010 regarding the genetic causes of facioscapulohumeral muscular dystrophy, or FSHD.

The team, co-led by Stephen Tapscott, M.D., Ph.D., a member of the Hutchinson Center's Human Biology Division, discovered that a rare variant of FSHD, called type 2, which accounts for about 5 percent of cases, is caused by two genetic mutations that together cause the production of muscle-damaging toxins responsible for causing symptoms of this progressive muscle disease.

Specifically, the 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. "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." 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 characterized by a progressive, gradual loss of muscle strength, particularly in the upper body.
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In addition to Tapscott and other Hutchinson Center researchers, other key members of the research team included Daniel G. Miller, M.D., Ph.D., an associate professor of pediatrics at the University of Washington; Rabi N. Tawil, M.D., a professor of neurology at the University of Rochester Medical Center; and Silvère van der Maarel, Ph.D., a professor of medical epigenetics at Leiden University Medical Center in The Netherlands; plus investigators from Raboud University Nijmegen Medical Centre in The Netherlands and Nice University Hospital in France.

Funding for the research came from multiple institutions at the National Institutes of Health (National Institute of Neurological Disorders and Stroke, Clinical and Translational Science Awards Program, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Human Genome Research Institute and the National Genetics Institute), Friends of FSH Research, the Muscular Dystrophy Association, and the University of Rochester Medical Center Fields Center for FSHD and Neuromuscular Research.

At Fred Hutchinson Cancer Research Center, home to three Nobel laureates, interdisciplinary teams of world-renowned scientists seek new and innovative ways to prevent, diagnose and treat cancer, HIV/AIDS and other life-threatening diseases. The Hutchinson Center's pioneering work in bone marrow transplantation led to the development of immunotherapy, which harnesses the power of the immune system to treat cancer with minimal side effects. An independent, nonprofit research institute based in Seattle, the Hutchinson Center houses the nation's first and largest cancer prevention research program, as well as the clinical coordinating center of the Women's Health Initiative and the international headquarters of the HIV Vaccine Trials Network. Private contributions are essential for enabling Hutchinson Center scientists to explore novel research opportunities that lead to important medical breakthroughs. For more information visit www.fhcrc.org or follow the Hutchinson Center on Facebook, Twitter or YouTube.

Fred Hutchinson Cancer Research Center

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