HLA-DRB1*15021 is the predominant allele in Japanese patients with juvenile dermatomyositis

Objective. To investigate HLA molecules and genes in Japanese patients with juvenile dermatomyositis (JDM). Methods. Twelve patients (8 girls and 4 boys) with ages of onset between 3 and 15 years were included. HLA class I antigen phenotypes were serologically typed by the Terasaki-NIH standard method. DNA was extracted from peripheral blood leukocytes using the phenol-chloroform extraction procedure, and stored at -70degreesC until use. Genomic DNA for HLA-DRB1, HLA-DQA1, and HLA-DQB1 alleles in JDM patients and controls was determined by the direct sequence method. Results. HLA-A24 and B52 were each detected in 7 cases (OR = 0.86, 5.02, p = 0.930, 0.006, respectively). HLA-DRB1*15021 was observed in 7 patients. This was significantly more frequent than occurred in the controls (OR = 5.72, p = 0.002). Seven patients out of 12 (58%) had the combination HLA-B52, DRB1*15021, DQA1*0103, and DQB1*0601. Conclusion. Our results suggest that the susceptibility gene for JDM either is HLA-DRB1*15021 or is present near the HLA-DRB1 locus. This differs from previous reports that describe the association with HLA-DQA1*0501 in Caucasian patients with JDM. The combination HLA-B52, DRB1*15021, DQA1*0103, and DQB1*0601 may contribute to the pathogenesis of JDM in Japanese patients.