Myostatin and its implications on animal breeding: a review

Summary Myostatin, or growth and differentiation factor 8 (GDF8), has been identified as the factor causing a phenotype known as double muscling, in which a series of mutations render the gene inactive, and therefore, unable to regulate muscle fibre deposition. This phenotype occurs at a high frequency in some breeds of cattle such as Belgian Blue and Peidmontese. Phylogenetic analysis has shown that there has been positive selection pressure for non‐synonymous mutations within the myostatin gene family, around the time of the divergence of cattle, sheep and goats, and these positive selective pressures on non‐ancestral myostatin are relatively recent. To date, there have been reports of nine mutations in coding regions of myostatin that cause non‐synonymous changes, of which three cause missense mutations, including two in exon 1 and one in exon 2. The remaining six mutations, located in exons 2 and 3, result in premature stop codons, which are the mutations responsible for the double‐muscling phenotype. Unfortunately, breed management problems exist for double‐muscled cattle, such as birthing difficulties, which can be overcome through genetically controlled breeding programmes, as shown in this review.