HLA class II genotyping of sarcoidosis patients in Hokkaido by PCR-RFLP.

To confirm the significant association of sarcoidosis with HLA-DR5, -DR6, and -DR8 associated DRB1 alleles, in sarcoidosis patients from the eastern Japan (Kanto) area found in our previous study, we used HLA class II genotyping of patients in another region-Hokkaido, in northern Japan. The annual incidence of sarcoidosis in Hokkaido is about three times that of eastern Japan, and Hokkaido has one of the world's highest incidences of this disease. For the HLA class II (HLA-DRB1, -DRB3, -DQA1, -DQB1) genotyping, we used the polymerase chain reaction restriction fragment polymorphism (PCR-RFLP) method with 150 subjects: 40 sarcoidosis patients and 110 healthy controls. The frequencies of DRB1*12, DRB1*14, DRB1*08, DQA1*0501, and DQB1*0301 were significantly increased in the patients, compared with the controls. Our finding of a high frequency of DRB1*08 (which lacks the DRB3 gene encoding the DR52 antigen) in patients living in both eastern Japan and in Hokkaido, confirms that it is the HLA-DRB1 locus, rather than that of the HLA-DRB3, -DQA1, or -DQB1, which determines the susceptibility to sarcoidosis.