Genetic Epidemiology Of Systemic Lupus Erythematosus

Objective To evaluate genetic mode of systemic lupus erythematosus (SLE ), to study the relationships of HLA-G gene polymorphism with SLE and auto-antibodies, and to explore genetic factors, environmental factors, behavioral life way, psycho-social factors and interaction between environmental factors and HLA-G gene contributing to systemic lupus erythematosus.Methods A case-control study was used to estimate genetic mode and to analyze association of HLA-G gene with systemic lupus erythematosus and auto-antibody. Genome DNA in the leukocyte was extracted by the phenol-trichloromethane extraction method. HLA-G gene polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP). Auto-antibodies were detected by indirect immunofluorescence test (IIFT). The influencing factors for SLE was analyzed by univariate and multivariate unconditional logistic regression. The interaction between environmental factors and HLA-G gene contributing to systemic lupus erythematosus was also analyzed by logistic regression model.Results Study on genetic mode of SLE showed the order of prevalence rate was as follows: first-degree relatives>second-degree relatives>third-degree relatives> control relatives. A ratio of s/q approached \l-Jq with Penrose's method. Heritability of SLE was 78.8%?.45% in first-degree relatives, 58.8%?0.9% in second-degree relatives and 39.2%?2.0% in third-degree relatives, and the summing up powered heritability was 75.2%?.12%. Six genotypes such as HLA-G*I/I, HLA-G* II / II, HLA-G*!/ II, HLA-G* IV / IV, HLA-G* II / IV and HLA-G* I/IV were found, but HLA-G* III alleles was not found in this study. There was significant difference in HLA-G* I /IIheterozygous cell between case and control groups, but no difference after correction. The other HLA-G genotypes and HLA-G alleles were not related with SLE. At the same time, the correlation of HLA-G alleles and genotypes with auto-antibodies were not found, Six environmental factors were related with systemic lupus erythematosus with multivariate unconditional logistic regression model, in which extravert was a protective factor for SLE and delay of age of menarche, spontaneous abortion history, house damp, sunlight stimulation and frequent tonsillitis were risk factors for SLE. There were interactions between HLA-G*I/I genotype and frequent tonsillitis, HLA-G* II / II genotype and rubella or urticaria history, HLA-G* I / IV genotype and sunlight stimulation.Conclusions SLE has characteristic of polygenic disease. Genetic factor plays an important role in the liability of SLE. HLA-G gene may not be related with SLE and auto-antibodies. There are many influencing factors and HLA-G gene-environment interaction contributing to systemic lupus erythematosus.