ICOS and autoimmune thrombocytopenic purpura: We observed increased frequencies of heterozygous minor genotypes of TIM3 rs10515746, CD28 rs1980422, and the homozygous minor allele of ICOS rs6726035 in ITP patients compared with healthy controls, while only CD28 rs1980422 remained significant under the codominant model after FDR correction (p = 0.002).