Because of high homology between myostatin and other growth factors of the transforming growth factor β (TGF-β) family, high specificity against myostatin is necessary to avoid previously observed side effects of the first clinically tested compounds in Duchenne muscular dystrophy (DMD) (gingival bleeding, telangiectasias, and hormonal level changes).99 The gene discussed is TGFB1; the disease is Duchenne muscular dystrophy.