Association between human beta defensin-1 single nucleotide polymorphisms and susceptibility to pulmonary tuberculosis]

To investigate the possible association between the SNP in the 5' untranslated region (5' UTR) of the human beta defensin 1 (DEFB1) gene and the susceptibility to pulmonary tuberculosis (PTB) in Chinese Han population.In this case-control study, venous blood was collected from 102 patients with PTB and 148 healthful persons. Genomic DNA was extracted using whole blood DNA extraction kit. The -52A/G, -44C/G and -20A/G SNP were genotyped by PCR-directed sequencing. The genotypes and allele frequency were analyzed using the χ(2) test. The linkage disequilibrium and haplotype were analyzed by SHEsis software.A total of 102 patients with PTB (69 males and 33 females, (53.42 ± 20.22) years old) and 148 healthy control cases (95 males and 53 females, (50.67 ± 14.53) years old) were enrolled, with no difference in gender and age (all P values > 0.05). DEFB1 -44 CC genotype was significantly more frequently found in PTB patients than in control group (81.4% (83/102) vs 66.9% (99/148), χ(2) = 5.114, P < 0.05, OR = 2.096, 95%CI: 1.095 - 4.011), so was -44C allele (89.2% (182/204) vs 80.4% (238/296), χ(2) = 6.975, P < 0.05, OR = 1.576, 95%CI: 1.086 - 2.286). No difference in -52 A/G and -20 A/G SNP was observed between the two groups. The proportion of the GGG (-52/-44/-20) haplotype was lower in PTB patients than in the control group (0.030 vs 0.081, χ(2) = 5.629, P < 0.05, OR = 0.348, 95%CI: 0.140 - 0.863). No linkage disequilibrium was found among the SNP of the three sites (D' values were 0.132, 0.064, 0.088; r(2) values were 0.003, 0.002, 0.003; all P values > 0.05).These results suggest that the SNP of DEFB1 5' UTR is associated with susceptibility to PTB in Chinese Han population. -44 C→G SNP and the related haplotype (GGG) might play a protective role in the pathogenesis of PTB.