X chromosome and female bias in systemic lupus erythematosus: Focus on population-based evidence

Polymorphisms of BLK are associated with renal disorder in patients with systemic lupus erythematosus

Previous studies are inconclusive on the relationships between BLK gene polymorphisms and clinical features of systemic lupus erythematosus (SLE). The present study aimed to estimate association between BLK loci and SLE clinical features in Chinese population. Associations between BLK single-nucleotide polymorphisms (SNPs) and susceptibility to SLE in this study were estimated using data of 1205 health controls previously reported in the same population. And a total of 814 SLE patients recruited from two different sources according with ACR criteria were analyzed for genotype-phenotype associations. A meta-analysis was conducted of the associations between BLK loci and renal disorder in SLE. The expression quantitative trait locus (eQTL) data were also extracted from the public databases for the selected SNPs. Significant associations were observed between these SNPs and susceptibility to SLE. In addition, the data showed that rs2618479 and rs7812879 were associated with renal disorder [OR = 1.51 (95% CI: 1.15, 1.99) and 1.61 (95% CI: 1.21, 2.14), P_corr = 0.033 and 0.011, respectively] and proteinuria [OR = 1.47 (95% CI: 1.12, 1.95) and 1.52 (95% CI: 1.14, 2.03), P_corr = 0.048 and 0.040, respectively]. The consistent associations were observed in two independent centers as well as new cases group. The result of meta-analysis for rs2618479 was also significant [OR = 1.35 (95% CI: 1.12, 1.62)]. In addition, bioinformatics analysis demonstrated that the two SNPs were significantly associated with the expression of BLK in whole blood and several immune cells. Our data support that variant loci of BLK are associated with presence of renal disorder in patients with SLE.

Association study between X-linked susceptibility genes and clinical features in Chinese female patients with systemic lupus erythematosus

Recent large-scale genetic association studies have identified that several single nucleotide polymorphisms (SNPs) on X chromosome are correlated with risk of systemic lupus erythematosus (SLE) in Chinese population. The aim of this study was to estimate association between these loci and clinical features in female patients with SLE. Six SNPs identified in previous studies were genotyped. Odds ratio (OR) was calculated with adjusting for potential confounding factors. A total of 772 SLE patients were included in the final analysis. The data showed that 3 SNPs (rs5914778, rs3853839 and rs1059702) were marginally associated with several clinical subphenotypes. Furthermore, consistent associations were also found in two independent cohorts. However, the cumulative genetic risk score (GRS) was not associated with clinical manifestations as well as the disease activity index at disease diagnosis. In summary, genetic variants in X-linked genes may be potentially associated with presence of specific clinical feature. Further studies in distinct ethnical populations are required to clarify the association between these loci and presence of SLE clinical features.