The FCGR3A F158V polymorphism was significantly associated with immune thrombocytopenia in all four genetic models tested (dominant: OR = 2.67, 95% CI 1.94-3.67, for FV + VV vs. FF, recessive: OR = 2.38, 95% CI 1.78-3.19, for VV vs. FF + FV, overdominant: OR = 1.58, 95% CI 1.15-2.17, for FV vs. FF+VV, and allele comparison: OR = 1.97, 95% CI 1.70-2.29, for V vs. F, in the overall analyses). This evidence concerns the gene FCGR3A and autoimmune thrombocytopenic purpura.