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High-throughput Quantitative Real-time RT-PCR Assay for Determining Expression Profiles of Types I and III Interferon Subtypes
Published on: March 24, 2015
IFN-γ promoter polymorphisms do not affect QuantiFERON® TB Gold In-Tube test results in a Canadian population
S Kiazyk1, L Larcombe2, C Lopez3
1National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg , Departments of Medical Microbiology.
Background:
Several studies have shown polymorphisms within the interferon-gamma (IFN-γ) promoter influence cytokine expression. The interferon-gamma release assay (IGRA) relies on the ability to produce IFN-γ in response to tuberculosis (TB) specific antigens. This study determined the relationship between the IFN-γ +874 A/T promoter polymorphism and the performance of the QuantiFERON®-TB Gold In-Tube (QFT-GIT) test in an ethnically diverse Canadian population.
Methods:
A total of 190 participants were categorised into three groups based on history of and exposure to TB: active TB (n = 55), TB exposed (n = 55) and presumably TB unexposed controls (n = 80). All participants underwent QFT-GIT testing, and DNA was extracted from whole blood and probed for polymorphism at position +874 (T/A) of intron 1 of IFN-γ. Statistical relationships between the QFT-GIT results, polymorphisms and demographic data were evaluated.
Results:
IFN-γ +874 genotype frequencies among the entire study population (n = 190) were A/A (45.8%), T/A (39.5%), and T/T (14.7%). Among the three study groups, there was no correlation between QFT-GIT results and the IFN-γ +874 A/T genotype, and no correlation of genotype with IFN-γ production in response to either Mycobacterium tuberculosis antigens or mitogenic stimulation.
Conclusion:
Our results indicate that the IFN-γ +874 promoter polymorphism does not influence QFT-GIT performance in this study population.
