Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by decrease of the platelet count and increased risk of mucocutaneous bleeding. Multiple factors have been demonstrated in ITP pathogenesis, including the genetic variants. Tumor necrosis factor-induced protein 3 (TNFAIP3) gene encodes the ubiquitin-modifying enzyme A20 which limits inflammation by terminating NF-κB activation through several signaling pathways including TNF and Toll-like receptors and regulates immunostimulatory effects of dendritic cells and attenuates antigen presentation. Single nucleotide polymorphisms (SNPs) of TNFAIP3 have been associated with susceptibilities to several autoimmune diseases. Therefore, we speculated that TNFAIP3 polymorphisms might be associated with the susceptibility of chronic ITP in Chinese population. We investigated the distribution of TNFAIP3 (rs2230926 and rs5029939) polymorphisms in 222 patients with chronic ITP and 153 controls by polymerase chain reaction-restriction fragment length polymorphism and direct sequencing. We observed significant difference in the allelic and genotypic distributions of rs2230926 and rs5029939 between the ITP and control groups (p < 0.05). Stratified analysis by gender revealed the association of rs2230926 polymorphism with chronic ITP in male groups. However, none of the two polymorphisms contributed to the onset age of chronic ITP. These data suggest an association of TNFAIP3 SNPs with susceptibility to chronic ITP. Together with previous reports, our finding provides further evidence for TNFAIP3 being a general autoimmunity gene.
Keywords: Chinese; polymorphism; primary immune thrombocytopenia; tumor necrosis factor-induced protein 3 gene.