In mouse models of HF, myocardial infarction (MI) induced by ligating the left coronary artery, led to skeletal muscle abnormalities, exercise intolerance and eventually to HF (94) and inhibition of XO by febuxostat/allopurinol was shown to prevent XO-derived ROS (H2O2) overproduction in XO-expressing tissues and skeletal muscle abnormalities and exercise intolerance (94, 117) suggesting inhibition of XO-derived ROS production can prevent skeletal muscle abnormalities. The gene discussed is XDH; the disease is hydrops fetalis.