Abstract: Objective To explore the significance of genetic factor in the pathagenesis of systemic lupus erythematosus(SLE).Methods A case-control study of 166 SLE probands and 383 controls was performed to analyze the effect of genetic factor on the liability of SLE.Falconer's methed was used to estimate the heritability.Results 20(12.05%)of 166 probands had one or more first-degree relatives suffered from SLE.Prevalence rates of SLE in first-degree relatives and second-degree relatives in proband group were 1.698% and 0.606%,respectively,which were significantly higher than that in control group(0.1115%)(P<0.01).Furthermore,the odd ratio(OR) and its 95% confidence interval(95%CI) were 14.88(4.22~62.70)and 5.31(1.38~23.95),respectively.The order of prevalence rates was as follows:first-degree relatives>second-degree relatives>third-degree relatives>control relatives.A ratio of s/q approached 1/√q with Penrose's method.Heritability of SLE was 78.8%±4.45% in the first-degree relatives,58.8%±10.9% in the second-degree relatives,and 39.2%±32.0% in the third-degree relatives.The weighted mean heritability was75.2%±4.12%.Conclusions SLE has characteristics of polygenic disease.Genetic factor might play an important role in the liability of SLE.

Key words: Systemic lupus erythematosus, Heritability, Prevalence rate, Proband