MYH7's a gene encoding a myosin heavy chain beta (MHC-β) isoform (slow twitch) expressed primarily in the heart. Changes in the relative abundance of MHC-β and MHC-α (MYH6, the fast isoform of cardiac myosin heavy chain) correlate with the contractile velocity of cardiac muscle. In early fetal development, MHC-β's predominately expressed in the ventricles, while MHC-α's predominantly expressed in the atria. In healthy adult hearts, MHC-α's predominantly expressed in… (More on Myh7)