By studying the predisposing gene in familial or sporadic ITP, Peng et al. show that the p.G76S mutation on the TNFRSF13B gene in ITP patients may lead to enhanced binding ability of APRIL ligands to B cells as well as increased BAFF levels [17]. The gene discussed is TNFRSF13B; the disease is autoimmune thrombocytopenic purpura.