Myostatin (GDF-8) as a potential quantitative trait locus in swine

Introduction Myostatin (GDF-8) is a member of the TGF-β superfamily of growth factors which is expressed predominantly in skeletal muscle. Myostatin is a purported negative regulator of muscle development (McPherron et al., 1997). Myostatin knock-out mice (mice which have the myostatin gene specifically inactivated) have individual muscles which can weigh 2 to 3 times more than the same muscles in wild-type control mice. Furthermore, the double-muscled body type of Belgian Blue and Piedmontese cattle has been linked to an inactive myostatin gene (McPherron and Lee, 1997). The loss of myostatin activity causes these cattle to be extremely muscular and lean. Porcine studies have shown that runt piglets have increased myostatin expression when compared to the more heavily muscled control piglets (Shaoquan et al., 1998).