Detection of two non-synonymous SNPs in SLC45A2 on BTA20 as candidate causal mutations for oculocutaneous albinism in Braunvieh cattle
Homozygosity for a large deletion in the solute carrier family 45, member 2 (SLC45A2) gene causes oculocutaneous albinism (OCA) in the Doberman Pinscher breed. An albino Lhasa Apso did not have this g.27141_31223del (CanFam2) deletion in her SLC45A2 sequence. Therefore, SLC45A2 was investigated in this female Lhasa Apso to search for other possible variants that caused her albinism. The albino Lhasa Apso was homozygous for a nonsynonymous substitution in the seventh exon, a c.1478G>A base change that resulted in a glycine to aspartic acid substitution (p.G493D). This mutation was not found in a wolf, a coyote, or any of the 15 other Lhasa Apso dogs or 32 other dogs of breeds related to the Lhasa Apso. However, an albino Pekingese, 2 albino Pomeranians, and an albino mixed breed dog that was small and long haired were also homozygous for the 493D allele. The colored puppies of the albino Lhasa Apso and the colored dam of the 2 albino Pomeranians were heterozygous for this allele. However, an albino Pug was homozygous for the 493G allele and therefore although we suggest the 493D allele causes albinism when homozygous in several small, long haired dog breeds, it does not explain all albinism in dogs. A variant effect prediction for the albino Lhasa Apso confirms that p.G493D is a deleterious substitution, and a topology prediction for SLC45A2 suggests that the 11th transmembrane domain where the 493rd amino acid was located, has an altered structure.