Objective: Development of systemic lupus erythematosus (SLE) is not only associated with single loci of HLA gene, but also possibly related to certain haplotypes and genotypes of MHC. In the present study the authors explored association of HLA-A, B, DR haplotype and genotype with SLE in Chinese children, analyzed a large family with multiple SLE patients and genetic origin of SLE patients with HLA-DRB1 * 15, to discover the influence of linkage disequilibrium of HLA gene on SLE.
Methods: HLA-A, B, DR alleles were tested in 53 patients with SLE and 40 cases with their parents, 35 patients with SLE and HLA-DRB * 15 positive and 27 cases with their parents, a large family with SLE (18 members of three generations) and also 78 normal controls and 43 cases with their parents by microlymphocytotoxicity test and polymerase chain reaction - sequence specific primers (PCR-SSP). HLA-A, B, DR haplotype and genotype of SLE patients and controls were statistically calculated. The SLE patients with HLA-DRB1 * 15 and controls were analyzed for either the gene originated from the paternal or the maternal side.
Results: The variety of the haplotype in patient group (64/80) was less than that in control group (74/86). Only 9 haplotypes were found common between the patient group and control group. The frequency of the haplotype HLA-A9B40DRB1 * 15 was significantly higher in patient group than that in control group (P < 0.05), RR was 10.726 0. Five members of the large family had haplotype A9B40DRB1 * 15, 2 of them were patients with SLE, 1 of them was positive for ANA and had Raynaud's phenomenon and 2 of them were normal. The rest of the family members were normal. The frequency of genotypes DRB1 * 09/DRB1 * 15 and DRB1 * 03/DRB1 * 15 in SLE group was significantly higher than that of control group (P < 0.05), RR was 7.772 7 and 14.272 7, respectively. The number of SLE children with gene HLA-DRB1 * 15 derived from their fathers was significantly higher than that of the children with the gene derived from the mothers.
Conclusion: These findings suggested that haplotype HLA-A9B40DRB1 * 15 and genotypes HLA-DRB1 * 09/DRB1 * 15, HLA-DRB1 * 03/DRB1 * 15 were correlated with SLE. The predisposition of multiple loci seems to have an additive effect. The children with their gene HLA-DRB1 * 15 derived from their fathers might more easily suffer from SLE than those with the gene derived from their mothers, the underlying mechanism needs further studies.