HLA CLASS II GENETIC POLYMORPHISM IN JAPANESE PSORIASIS VULGARIS.
          K.Osawa, T.K.Naruse, Y.Nose, A.Ozawa, M.Ohkido, H.Inoko. Dept. of Molecular Life Science and Dept. of Dermatology, Tokai University School of Medicine, Kanagawa, Japan .
          Susceptibility of Psoriasis Vulgaris (PV) has been reported to be strongly associated with HLA Cw6 and Cw7, and so the causative gene for PV has been supposed to be the HLA-C gene itself or its nearby gene. However, HLA class II alleles have not been well analyzed yet in Japanese PV patients. In this study, we performed HLA-DQA1, DQB1, DRB1 and DPB1 allele typing using the PCR-RFLP (polymerase chain reaction restriction fragment length polymorphism ) method in 48 Japanese PV patients and analyzed their frequencies in the patients compared with 136 Japanese healthy individuals. In our results, DQA1*0103 was significantly increased (62.5% vs 28.7%, RR=3.67, p=0.00004) and DQB1*0601 in strong linkage disequilibrium with DQA1*0103 was also significantly increased (60.4% vs 27.9%, RR=3.94, p=0.00007). Only one patient lacked DQB1*0601 out of the 30 patients who have DQA1*0103. Moreover DRB1*1502 (33.3% vs 16.9%, RR=2.30, p=0.016) and DRB1*0803 (29.2% vs 14.0%, RR=2.61, p=0.018) were also significantly increased probably as a result of strong linkage disequilibria to DQA1*0103-DQB1*0601 as two of the major common haplotypes in Japanese. Further, DQA1*0201, DQB1*0201 and DRB1*0701 combination (6.3% vs 0%, RR=21.47, p=0.017) was found in 3 patients, where each allele is rare in Japanese. Therefore these patients probably have the same haplotype of DQA1*0201-DQB1*0201-DRB1*0701 that is one of the strongly associated haplotypes with the disease in Caucasians. On the other hand, DQA1*0101, DQB1*0501, DRB1*0101, DRB1*0403 and DPB1*0402 were significantly decreased and so these alleles may be protective genetic factors against PV. In conclusion, we analyzed HLA class II alleles for Japanese PV patients by the PCR-RFLP method, and DQA1*0103 and DQB1*0601 alleles are more significantly increased than other alleles. These results suggest that HLA-DQ is strongly associated with PV rather than HLA-DR, and HLA-DQ itself or its nearby gene should be one of the causative genes and might be responsible for the development of PV in addition to HLA-C or its nearby gene.