For a prior probability of 0.1, the FPRP values indicated that four genetic models (FAS −670 A/G: GG vs. GA; FAS −1377 G/A: A vs. G; FAS −1377 G/A: AA vs. GG; FAS −1377 G/A: AA+AG vs. GG) of the FAS −670 A/G and −1377 G/A polymorphisms were truly associated with an increased risk of autoimmune diseases (FPRP = 0.262, 0.073, 0.173, and 0.085, respectively). The gene discussed is FAS; the disease is autoimmune disease.