A PCR sequence-specific oligonucleotide probing (PCR-SSOP) method has been adopted for typing of HLAA, -B, and -DRB1 genes in the Japanese population. The method targets alleles observed at more than 0.1% gene frequency in the Japanese population. Using 13, 24, and 17 probes for HLA-A, -B, and -DRB1 genes, respectively, the method enabled us to discriminate HLA alleles or at least serological groups even in heterozygous samples. We set the washing temperature for a total of 54 probes to a single temperature (55oC). Approximately one hundred known samples for all three HLA genes could be typed correctly except one variant sample for HLA-A. A PCR primer did not work efficiently for one of the hetrozygous alleles of the variant sample because it has a sequence substitution in the target portion of the intron. The method could be improved using mixed primers that also target the variant sequence. It is also possible to amplify DNA efficiently and type HLA genes using blood samples on filter paper.

Background. The association between IgA nephropathy (IgAN) and serologically determined HLA-DR4 has been firmly established in various ethnic groups. The recent development of DNA typing of the HLA class II system has allowed precise determination of HLA genotypes, and provided new insights into the pathogenesis of this disorder. Here we analyzed HLA class II genotypes in Japanese patients with lgAN to determine the role of genetic factors in pathogenesis of this disease. Patients and Methods. HLA class II genes were analyzed in 165 unrelated Japanese patients with biopsy-confirmed IgAN using polymerase chain reaction (PCR)-based sequence-specific oligonucleotide probe hybridization. Results. HLA-DR4 correlated with IgAN in Japanese patients. DNA typing also showed a significant correlation between IgAN and HLA-DRB1*0405 and HLA-DRB1 * 1501 genotypes. We also found the correlation between the frequency of HLA class II genotypes and various clinical parameters. We found that HLA-DRB I *0405 and DQB1 *0303 were associated with a broad range of clinical features including severity of renal dysfunction, and that HLA-DRB I * 1 501 was associated with proteinuria of > 1g per day, and with high serum IgA concentrations. Conclusion. We report here the association of IgAN with HLA-DRBI *0405, -DRB 1*1501 and -DQB 1 *0303 in Japanese patients. The presence of these alleles correlated with distinct clinical findings, which may reflect heterogeneity of both the pathogenesis and genetic background of the disease.