Genetic research in systemic lupus erythematosus (SLE) is rapidly developing, and numerous sets of genes are being associated with specific clinical subphenotypes in the setting of SLE. On the other hand, basic science studies are revealing strong connections between salt-water balance and inflammation. The aim of this study was to evaluate whether variants of genes known to influence the individual susceptibility to hypertension also influence the renal function in a cohort of SLE patients with and without lupus nephritis (LN). This study is a case-control study with candidate gene approach. A total of 111 patients with SLE (50 with SLE without nephritis, 55 with LN and 6 with simple urinary sediment abnormalities) and 62 healthy controls (HC) were genotyped for NCX1 rs11893826 (NCX1a) and rs434082 (NCX1b) and ADD2 rs4984 SNPs. Patients with ADD2 CT genotype were protected from LN and skin involvement; ADD2 CC | NCX1a AA/AG genotypes were associated with the presence of anti-cardiolipin antibodies; NCX1a AA genotype was slightly more frequent in lupus patients than in HC and associated with relapse risk and higher creatinine in patients with LN. NCX1b GG patients with LN had increased chances to reach complete remission. NCX1b GG | NCX1a GG genotype is associated with joint involvement. ADD2 and NCX1 variants influence the risk and the clinical features of SLE and LN, highlighting their potential role in regulating systemic inflammation and/or the local response to immune-mediated injury.
Keywords: Anti-phospholipid antibodies; Arthritis; Beta-adducin; Nephritis; Skin; Sodium–calcium exchanger 1; Systemic lupus erythematosus.