Our meta-analysis showed that the FAS -670 A/G polymorphism was associated with the risk of autoimmune diseases (GG vs. GA: OR=1.079, 95% CI=1.004-1.160, P=0.038), especially in Caucasians (GG vs. GA: OR=1.12, 95% CI=1.03-1.23, P=0.012), Asians (G vs. A: OR=0.89, 95% CI=0.83-0.96, P=0.002), systemic lupus erythematosus (SLE) (G vs. A: OR=0.85, 95% CI=0.77-0.94, P=0.001), multiple sclerosis (MS) (GG+GA vs. AA: OR=0.83, 95% CI=0.70-0.99, P=0.043), systemic sclerosis (SSc) (GG vs. GA: OR=1.20, 95% CI=1.07-1.36, P=0.003) and Hashimoto's thyroiditis (HT) (G vs. A: OR=1.45, 95% CI=1.10-1.90, P=0.008); the FAS -1377 G/A polymorphism was associated with the risk of autoimmune diseases (A vs. G: OR=1.11, 95% CI=1.03-1.20, P=0.008), especially in Asians (A vs. G: OR=1.15, 95% CI=1.05-1.25, P=0.002) and high quality studies (A vs. G: OR=1.14, 95% CI=1.05-1.24, P=0.002).
In this connection, deficiency of vitamin D has been associated with several autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), Hashimoto Thyroiditis (HT), and multiple sclerosis (MS).