The ratio of CD4∶CD8 was decreased in ITP patients (median, 1.42; range, 0.26–4.18) compared to healthy controls (median, 1.90; range, 0.93–3.95; P = 0.029), and the percentage of CD8+ T cells was increased in ITP patients (median, 29.34%; range, 9.78–68.97%) compared with healthy controls (median, 22.35%; range, 12.89–32.3%; P = 0.025). This evidence concerns the gene CD8A and autoimmune thrombocytopenic purpura.