86, 95% CI: 1 04–3 31) and log-additive (OR: 1 35, 95% CI: 1 02–1

86, 95% CI: 1.04–3.31) and log-additive (OR: 1.35, 95% CI: 1.02–1.80) inheritance models. Akaike’s information criterion (AIC) is a measure of the goodness of fit of an estimated statistical model, and it can judge a model by how close its fitted values tend to be to the true values, in terms of a certain expected value. Because of the smaller AIC value (565.6), the log-additive model was accepted as the best fit for these data [30]. The result of association analysis for the haplotype of SNP4/SNP5/SNP6/SNP7 was consistent

with individual SNP analysis in our study (P = 0.00079). This suggests that at least one susceptibility locus for tuberculosis lies within or very close to the region that spans SNP4/SNP5/SNP6/SNP7 selleck chemical see more in ifngr1 in the Chinese Han population, because haplotype has more accuracy and statistical power than individual SNP in LD-based association studies. In addition, the haplotype of SNP4/SNP5/SNP6/SNP7 contained two alleles that are hypothesized to have lower promoter activity, SNP5 (rs1327474, G>A) and SNP4 (rs2234711, T>C), which further explained the reason for the haplotype to be associated with susceptibility to tuberculosis. It is known that patients with complete loss-of-function or TT-deletion alleles of ifngr1 primarily present DNA ligase with a clinical picture

of infection with mildly virulent mycobacteria or Bacille Calmette-Guérin, which occurs usually during early childhood or after vaccination [29, 31]. The sequence around −470delTT

(SNP7) of the ifngr1 gene is reminiscent of a signal transducer and activator of transcription 1 (STAT1) binding site (TTCCtcaAA), and the ifngr1−470delTT allele abolishes the crucial first two positions of this binding motif. In our selected population, no such mutation was found for TTdel of −470delTT. Our results in the Korea population were similar to those in Caucasians. There was also a low frequency of −470delTT in African-Americans [29, 31]. These data showed that −470delTT (SNP7) was a rare mutation and was not distributed widely in the Chinese populations. In addition, the result implied that differences in genotype frequency existed among the populations. In conclusion, we found that SNP6 (A/G) in ifngr1 or nearby genes might be implicated in predisposition to tuberculosis. In addition, the C-A-A-TT haplotype, which included the two alleles that are hypothesized to have lower promoter activity, was associated with susceptibility to tuberculosis. Further studies are warranted to confirm these findings. Investigation of these polymorphisms will be of benefit to our understanding of host and pathogen interactions.

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