CTLA4 and autoimmune thrombocytopenic purpura: Interestingly, Kasamatsu et al. did not find a difference in + 49 A/G and CT60 A/G genotype between patients with ITP and HCs, but reported a correlation between CTLA4 CT60 GG genotype (low expression type) and severe clinical presentation at diagnosis while studying four CTLA-4 SNPs in 119 patients with chronic ITP [19].