A 3-bp deletion in the SLC45A2 gene is associated with loss of fleece pigmentation in black-fleeced Suffolk sheep

Sheep have naturally pigmented wool which interferes with dyeing. Selection has been carried out over many years to remove pigment, with substantial success, but most wool still contains some pigment. As an alternative to selection, it has been proposed to take a naturally occurring mutation found in black Suffolk sheep, that blocks wool pigmentation, and introgress it into other breeds. However, the nature of the mutation has not been identified, prompting us to characterise it. The Suffolk white-fleece phenotype is associated with a novel 3-bp deletion in the gene SLC45A2, which encodes a membrane bound transporter that mediates melanin synthesis. The deletion results in the removal of one amino acid from the protein. The assignment of this deletion as the likely causative mutation is supported by it: being homozygous in the genome of nine animals with a white fleece and not homozygous in the genomes of eight animals with a black fleece; having a high level of conservation of the encoded amino acid sequence in the region surrounding the deleted amino acid across Mammalia; and the same deletion (but in a compound heterozygous state) being found in human SLC45A2 in a person with albinism.