An Epistatic Effect of KRT25 on SP6 Is Involved in Curly Coat in Horses

The 2018 study involving 216 horses discovered that genetic variants in two different genes, KRT25 and SP6, independently affect the development of curly hair in horses. The KRT25 variant was found to cause both curly hair and hypotrichosis (hair loss), while the SP6 variant only resulted in curly hair. Horses with mutations in both genes developed curly hair and hypotrichosis. The study concluded that the KRT25 variant masks the effect of the SP6 variant, a phenomenon known as an epistatic effect. The research also suggested that the development of curly hair is not due to differential gene expression, but rather protein modifying effects.