CXCL13 rs355687 variant confers increased susceptibility to systemic lupus erythematosus in a Mexican population

C-X-C motif chemokine ligand 13 (CXCL13) regulates B-cell trafficking, lymphoid neogenesis, and adaptive immune responses, and its dysregulation contributes to systemic lupus erythematosus (SLE) pathogenesis. Nevertheless, how CXCL13 genetic variants influence SLE susceptibility remains unclear. This study investigated the association between the CXCL13 single-nucleotide variant (SNV) rs355687 and susceptibility to SLE. This study enrolled SLE patients and healthy blood donors. Genotyping of the rs355687 SNV was performed via real-time PCR, while serum CXCL13 levels were quantified by ELISA. Genotype and allele frequencies were compared between groups, and their association with SLE risk was evaluated under different genetic models. A total of 149 SLE patients and 98 healthy controls were studied. The rs355687 minor allele frequency was significantly lower in SLE patients than in controls. The TT genotype was associated with an increased risk of SLE under both additive (odds ratio [OR] = 1.77, 95% CI: 1.13–2.76; p = 0.01) and recessive (OR 2.03, 95% CI: 1.16–3.56; p = 0.01) models. Furthermore, median serum CXCL13 concentrations were significantly higher in patients carrying the TT genotype compared with controls (71.51 [IQR: 51.36–149.50] vs. 57.38 [IQR: 49.52–64.97] pg/mL; p = 0.02). The CXCL13 rs355687 SNV is associated with increased susceptibility to SLE, with the TT genotype specifically linked to elevated CXCL13 levels. These findings support the potential of this variant as a biomarker for disease susceptibility in SLE.