Association between ICOS polymorphisms and immune thrombocytopenia in an Iranian population

Context: Immune thrombocytopenia (ITP) is an autoimmune disease that is caused by the dysregulation of immune system, in which the circulating platelets (Plt) are destroyed by reticuloendothelial system, leading to hemorrhagic manifestations in patients. Aims: Recent studies have indicated that polymorphisms can contribute to ITP susceptibility and outcome. Given the importance of follicular helper T (Tfh) cells in ITP, we evaluated polymorphism in Inducible T-cell Costimulator (ICOS) as a Tfh surface marker among ITP patients to find a likely prognostic factor. Subjects and Methods: We recruited 54 ITP patients and 46 persons with no history of thrombocytopenia to conduct this case–control study. In addition to routine laboratory parameters, three polymorphisms, namely rs10932036, rs4404254, and rs10932037 of ICOS gene, were assessed by polymerase chain reaction. Statistical Analysis: Mann–Whitney, Kruskal–Wallis, and Chi-square tests were employed to compare and evaluate the data, and P < 0.05 indicated a statistically significant association. Results: The findings of our study showed that allele and genotype frequencies of all three polymorphisms in question were similar between case and control with no significant difference. However, our assessment indicated higher mean Plt counts in RS4404254 CC genotype than other genotypes under investigation. Conclusions: It seems that rs10932037, rs4404254, and rs10932036 polymorphisms of ICOS gene are not involved in susceptibility to ITP. Nevertheless, we found that those carrying RS4404254CC polymorphism have better prognosis due to higher Plt counts both in acute and chronic ITP patients.