The role of T-cell immunoglobulin- and mucin-domain-containing molecule-3 polymorphisms in idiopathic thrombocytopenic purpura

The family of T-cell immunoglobulin- and mucin-domain-containing molecules (TIMs) has an important role in immune regulation. TIM-3 is a transmembrane protein preferentially expressed on terminally differentiated Th1 cells and plays a role in T-helper (Th)-1-mediated autoimmune disease. Idiopathic thrombocytopenic purpura (ITP) is an acquired organ-specific autoimmune disease with a polarization of Th1. The purpose of this study was to investigate whether the -1516G>T, -574T>G, 4259G>T single-nucleotide polymorphisms within the TIM-3 gene contribute to the genetic susceptibility to ITP. Genotyping of TIM-3 -1516G>T, -574T>G, and 4259G>T was performed in 187 patients with ITP and 123 healthy individuals by polymerase chain reaction-restriction fragment length polymorphism assay. No significant differences existed in genotype and allele distributions between the patients with ITP and the controls in all three sites. There was strong linkage disequilibrium (LD; r2 = 0.633) between -574T>G and 4259G>T, whereas -1516G>T was not in LD with -574T>G (r2 = 0.007) or with 4259G>T (r2 = 0.002). The -1516G>T, -574T>G, and 4259G>T of TIM-3 gene polymorphisms might not play an important role as a genetic risk factor in the pathophysiology of ITP.