Human leukocyte antigen genotypes and antibody profiles associated with familial pemphigus in Japanese

Previous population-based, genetic studies have shown that human leukocyte antigen (HLA) class II loci such as HLA-DR4 (DRB1*04) and HLA-DR14 (DRB1*14) alleles are consistently associated with the occurrence of pemphigus vulgaris (PV) in Japanese as well as other ethnic populations. Among PV-related HLA-DRB1 alleles (*0406, *1401, *1405, *1406) in Japan, HLA DRB1*1405 and DRB1*0406 were found to be associated with both PV and pemphigus foliaceus (PF) phenotypes. We report four familial cases of pemphigus in two unrelated families, together with analysis of their HLA-DR and -DQ alleles, and their antibody profiles. One family comprised a woman with PF and her mother with PV: both patients shared a HLA haplotype of A31(19), B54(22), CW1 and DRB1*1405. Another family included two sisters with PF and PV, respectively: both of these patients shared a DRB1*1405-DQA1*0104-DQB1*0503 haplotype. Clinicopathological and serological monitoring revealed that the elder sister with PF presented with a PV phenotype later, and gained anti-desmoglein (Dsg)3 antibodies in addition to having a low titer of anti-Dsg1 antibodies. Conversely, the younger sister with PV developed PF with only anti-Dsg1 antibody detected. These results indicate that an HLA-DRB1*1405 (DQB1*0503) haplotype may confer susceptibility to both PV and PF, and that genetic susceptibility alone is not always responsible for the clinical phenotype and autoantibody profile.