Slug appears to be essential for precursor migration and melanocyte development in mammals; Slug knockout mice exhibit some features of the Waardenburg syndrome in humans, which is associated with hypopigmentation and hearing loss (Shirley et al., 2012), while loss of one Slug allele in humans is associated with piebaldism (Sanchez-Martin et al., 2003). Here, SNAI2 is linked to Waardenburg syndrome.