HLA‐DQB1 allele associates with idiopathic nephrotic syndrome in Japanese children

HLA‐DQA1 and ‐DQB1 genes were investigated in 30 Japanese children with idiopathic nephrotic syndrome (INS) using the polymerase chain reaction‐restriction fragment length polymorphism method. Compared with control children, there was a significant increase in the HLA‐DQA1 *0501, DQB1 *0301 and DQB1 *0601 alleles, whereas the frequency of DQB1 *0501 showed a significant decrease in the patients. The increase of DQA1 *0501 can be explained as being a result of a linkage disequilibrium with DQB1 *0301. The previous result demonstrating a positive association of DRw6 and DRw8 with INS is also assumed to be attributable to a linkage disequilibrium with DQB1 *0301 and 0601. A total of 83% of patients compared with 37% of controls possessed DQB1 *0301 and/or DQB1 *0601 allele ( P < 0.001, RR = 8.6). Only these alleles have alanine at residue 13 and tyrosine at residue 26 in the hypervariable region in the β1 domain of DQB1 gene. These findings suggest that the unique amino acid residues in the DQB1 gene may contribute to disease susceptibility in Japanese children with INS.