Association of the interferon-gamma single nucleotide polymorphism +874(T/A) with response to immunosuppressive therapy in patients with severe aplastic anemia.

The aim of this study was to investigate whether a single nucleotide polymorphism (SNP) +874T/A of interferon-gamma (IFN-γ) correlates with response to immunosuppressive therapy. Amplification refractory mutation system-polymerase chain reaction was used to amplify the polymorphic segments of the IFN-γ +874T/A gene in the samples obtained from 54 patients with aplastic anemia and 51 healthy adults. Further, enzyme linked immunosorbent assay was used to assay IFN-γ levels in the blood plasma of 35 patients with severe aplastic anemia before immune suppression therapy and 20 healthy blood donors. The results showed that the frequency of IFN-γ +874 TT genotype in patients with aplastic anemia was significantly higher than the corresponding frequency in the healthy adults (42.6% vs. 17.6%, χ(2)=13.78, p=0. 01). The response rate in severe aplastic anemia patients with increased IFN-γ levels in the blood plasma was higher than that in severe aplastic anemia patients with decreased IFN-γ levels in the blood plasma (73.7% vs. 25.0%, p<0.05). Of the 35 patients with severe aplastic anemia, 15 showed the IFN-γ +874 TT genotype, whereas response in 11 patients, the high response rate was significantly in the favor of the IFN-γ +874 TT genotype (73.3% vs. IFN-γ +874 non-TT 35%, p<0.05). In conclusion, the IFN-γ +874T/A gene polymorphism may be correlated with response to immunosuppressive therapy.