Genotype and allele frequencies of FcγRIIA H131R polymorphism. (A) Analysis of the 3 groups of patients (Ab^neg, Ab^pos, and HIT). HIT patients were also stratified according to the presence (HITT) or absence (HIT) of thrombotic complications. No information was available about thrombotic events in 5 HIT patients. (B) Analysis of H131R polymorphism in patients with venous thromboembolism (VTE) or stroke and in healthy subjects. P value was calculated using the χ² test. MAF, minor allele frequency.