On Sep. 4, 2024, an international consortium led by scientists from Uppsala University in Sweden reported that the speed of graying and susceptibility to melanoma are determined by the copy number of a small duplicated DNA sequence in the gene Syntaxin 17.

At an older age, white horses carrying the Grey mutation often develop skin melanomas that are usually benign but some are malignant. These horses have white hair but completely black skin and do not get melanoma because they are sensitive to UV damage, a major risk factor for human melanoma, but due to an intrinsic effect of the Grey mutation. The study results were published in Nature Communications