CHARLOTTESVILLE, Va., Dec. 18 (UPI) -- U.S. medical scientists have discovered a well known heart protein, NKX2-5, is linked with type-1 myotonic muscular dystrophy.

   Researchers at the University of Virginia Health System discovered that, in cases of type 1 myotonic muscular dystrophy, or DM1, NKX2-5 is overproduced in mice and people with DM1, yet it produces the same kind of heart problems associated with a deficiency of the protein.

   The scientists said DM1 is the most common form of muscular dystrophy in adults and NKX2-5 is a biomarker for heart stem cells, as well as being very important for the normal development of the heart.

   "Too little of it causes major cardiac problems including slow and irregular heartbeats," said Dr. Mani Mahadevan, a human genetics researcher and a professor of pathology who led the study.

   Mahadevan said excessive NKX2-5 might explain why as many as 70 percent of individuals with DM1 develop heart problems that cause their heartbeats to become slow and irregular, often necessitating the need for pacemakers.

The study is available in the online edition of the journal Nature Genetics.

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