Polymorphisms of the IL-23R gene are associated with primary immune thrombocytopenia but not with the clinical outcome of pulsed high-dose dexamethasone therapy.

Primary immune thrombocytopenia (ITP) is an autoimmune heterogeneous disorder that is characterized by decreased platelet count. The interleukin-23 receptor (IL-23R) has been identified as a susceptibility gene for the development of multiple autoimmune diseases. To investigate the possible association of IL-23R gene single-nucleotide polymorphisms (SNPs) with ITP and the association with the clinical outcome of pulsed high-dose dexamethasone (HD-DXM) therapy, four SNPs in the IL-23R gene, rs10889677, rs1884444, rs7517847, and rs11209032, were tested in a cohort of 75 ITP subjects and 81 controls by direct sequencing. IL-23R rs1884444 GT/TT variant genotypes were observed to be associated with significantly increased risk of ITP as compared with controls (GT/TT vs. GG: odds ratio (OR) 2.776, 95 % confidence intervals (CI) 1.086-7.090, p = 0.028). However, other three SNPs revealed no statistically significant differences between patients and controls (rs10889677 CA/AA vs. CC: OR 2.200, 95 % CI 0.727-6.661, p = 0.155; rs11209032 GA/AA vs. GG: OR 0.747, 95 % CI 0.379-1.472, p = 0.399; rs7517847 TG/GG vs. TT: OR 1.031, 95 % CI 0.544-1.956, p = 0.925). Furthermore, IL-23R SNPs revealed no association with clinical outcome of HD-DXM therapy. This study suggests that polymorphism in the IL-23R gene, rs1884444, indicates a significant association with susceptibility to ITP in a recessive genetic model but does not have association with the clinical outcome of HD-DXM therapy.