Identification of a new haplotype within the promoter region of the MSTN gene in horses from five of the most common breeds in Poland.

Myostatin (GDF-8) encoded by the MSTN gene is a negative regulator of muscle growth and development and belongs to the TGF-β superfamily of secreted growth and differentiation factors. In Thoroughbred horses, an MSTN sequence polymorphism (g.66493737C>T) is associated with optimum race distance.