New research shows that, in cases of type 1 myotonic muscular dystrophy, a well known heart protein does several surprising things. The protein, NKX2-5, is a biomarker for heart stem cells. It is also very important for the normal development of the heart. The researchers were surprised to find that mice and individuals with DM1 actually overproduce NKX2-5, yet experience the same kind of heart problems associated with too little of it.