Evaluation of genetic susceptibility between systemic lupus erythematosus and GRB2 gene

Multiple lines of evidence have shown that systemic lupus erythematosus (SLE) is attributable to both genetic and environmental factors. The product of GRB2 is a key factor in the activation of B cells and has been reported to be significantly associated with SLE in European populations. In the study, we aimed to investigate the relationship between GRB2 and SLE. A total of 1,710 Han Chinese women comprising 567 SLE patients and 1,143 controls were recruited to genotype 20 selected tagging SNPs. We tested the potential association between 13 clinical variables of SLE and the significant polymorphisms related to SLE. The eQTL data were extracted from the GTEx database to examine the functional consequences of the targeted SNPs. A significant association signal was identified between rs36023980 and SLE in both genotypic and allelic analyses (OR = 0.61, P = 0.0003). Complement inhibition was shown to be significantly associated with the genotypes of SNP rs36023980 in SLE patients (P_genotype = 0.003). Further stratification analyses showed that the genetic association signal of SNP rs36023980 on SLE could only be identified in cases with complement inhibition. SNP rs36023980 was also identified to be significantly associated with the expression of GRB2 in whole blood and sun-exposed skin. In conclusion, our findings confirm the results from the previous GWAS and are the first to report the association of GRB2 with SLE in Han Chinese population.