Large-Scale Polymorphism Analysis of Dog Leukocyte Antigen Class I and Class II Genes (DLA-88, DLA-12/88L and DLA-DRB1) and Comparison of the Haplotype Diversity between Breeds in Japan

Polymorphisms of canine leukocyte antigen (DLA) class I (DLA-88 and DLA-12/88L) and class II (DLA-DRB1) genes are important for disease susceptibility studies, but information on the genetic diversity among dog breeds is still lacking. To better elucidate the polymorphism and genetic diversity between breeds, we genotyped DLA-88, DLA-12/88L, and DLA-DRB1 loci using 829 dogs of 59 breeds in Japan. Genotyping by Sanger sequencing identified 89, 43, and 61 alleles in DLA-88, DLA-12/88L, and DLA-DRB1 loci, respectively, and a total of 131 DLA-88-DLA-12/88L-DLA-DRB1 haplotypes (88-12/88L-DRB1) were detected more than once. Of the 829 dogs, 198 were homozygotes for one of the 52 different 88-12/88L-DRB1 haplotypes (homozygosity rate: 23.8%). Statistical modeling suggests that 90% of the DLA homozygotes or heterozygotes with one or other of the 52 different 88-12/88L-DRB1 haplotypes within somatic stem cell lines would benefit graft outcome after 88-12/88L-DRB1-matched transplantation. As previously reported for DLA class II haplotypes, the diversity of 88-12/88L-DRB1 haplotypes varied remarkably between breeds but was relatively conserved within most breeds. Therefore, the genetic characteristics of high DLA homozygosity rate and poor DLA diversity within a breed are useful for transplantation therapy, but they may affect biological fitness as homozygosity progresses.