The impact of Fc gamma receptor IIa and IIIa gene polymorphisms on the therapeutic response of rituximab in Egyptian adult immune thrombocytopenic purpura.

Background In chronic immune thrombocytopenic purpura (ITP), rituximab removes the harmful autoantibodies through antibody-dependent cellular cytotoxicity. The response to rituximab in ITP is variable; the effectiveness of rituximab is influenced by the process of activation of effector fragment C gamma receptors (FcγRs). Genetic factors may affect the response to rituximab. Objectives The influence of FcγRIIa (H131R) and FcγRIIIa (V158F) gene polymorphisms on the response to rituximab in ITP. Methods One hundred ITP patients were genotyped for FcγRIIa (H131R) and FcγRIIIa (V158F) gene polymorphisms using the polymerase chain reaction-restriction fragment length polymorphism assay. The response at the end of the third month was assessed by direct platelets count. Polymorphisms were analyzed in relation to the response. Results The mean platelets count at end of weeks 1-4 of rituximab was statistically significantly higher in patients who achieved complete response (CR) than partial response or no response (P-value = .001). Although RR (44.4%) and HR (38.9%) genotypes were observed to be higher in patients who achieved CR compared with the wild (HH) genotype (16.7%), it was not statistically significantly different (P-value = .648). Conclusion The higher platelet count achieved early is predictive for a better response to rituximab later. FCγRIIA polymorphisms did not significantly influence response to rituximab in ITP.