FasL (rs763110) gene polymorphism is not associated with susceptibility to rheumatoid arthritis in Croatian population

AIM: To investigate the association of FasL gene polymorphism (rs763110) with rheumatoid arthritis occurrence, disease activity, and tumor necrosis factor-α (TNF-α) plasma concentration in Croatian patients, and to conduct an updated meta-analysis. METHODS: This cross-sectional study enrolled 81 patients with rheumatoid arthritis and 94 control patients. After the assessment of the Disease Activity Score (DAS)-28, blood was taken for analysis. DNA was isolated from the whole blood to determine FasL polymorphism (rs763110) by polymerase chain reaction. Protein levels of TNF-α were determined with ELISA. After a detailed literature search, we conducted an updated meta-analysis using the Review Manager 5 software. RESULTS: Rheumatoid arthritis patients had significantly higher TNF-α concentration in plasma (1.65 [1.2-2.42] pg/mL) than controls (0.99 [0.77-1.35] pg/mL, P < 0.001). The FasL rs763110 polymorphism was not associated with rheumatoid arthritis occurrence in either codominant, dominant, recessive, overdominant, or log additive model. Furthermore, the rs763110 genotype was not associated with DAS 28 score or TNF-α concentration. After we added our results to an updated meta-analysis, the significant association previously reported for Western Eurasians was abolished. CONCLUSION: Our data suggest that the association between FasL rs763110 polymorphism and RA susceptibility in Western Eurasians observed in previous studies might be overestimated and should be limited to the population of Southwestern Asia until further investigations are performed.