Polymorphism of the interferon-gamma gene and risk of tuberculosis in a southeastern Chinese population.

The aim of this study is to examine the influence of the +874 A/T and +875 CA microsatellite single nucleotide polymorphisms (SNPs) of the interferon-gamma gene (IFNG) on patients with tuberculosis (TB) in the southeastern Chinese population. Genomic DNA from patients with TB (n = 301) and ethnically matched controls (n = 310) was genotyped for the two SNPs by DNA sequencing and short tandem repeat-polymerase chain reaction (PCR) method. Our results demonstrated the AA genotype of +874 A/T IFNG was associated with TB (odds ratio, 1.98; 95% confidence interval = 1.08-3.63; p = 0.035). By grouping alleles into 12 and non-12 CA repeats at the +875 CA microsatellite, the homozygous non-12/non-12 CA repeats genotype yielded the same significant trend as that observed in the +874 AA genotype. The results indicate a positive association of IFNG polymorphism with TB. Data also provide genetic evidence supporting the multiple disease hypothesis, which emphasizes that many disease genes have been involved.