SFTPC genetic polymorphisms are associated with tuberculosis susceptibility and clinical phenotype in a Western Chinese Han population

Tuberculosis (TB) is one of the most common infectious diseases globally. The surfactant protein C (SFTPC), which is involved in innate immunity and surfactant function in the lung, may contribute toward the progression of TB. The aim of the present study was to preliminarily investigate the possible association of single nucleotide polymorphisms (SNPs) in the SFTPC gene with TB susceptibility and clinical phenotypes in a Western Chinese Han population. The improved multiplex ligation detection reaction method was used to genotype 6 SNPs in SFTPC, in 900 patients with TB and 1,534 healthy control subjects. It was found that the A allele for rs1124 and the C allele for rs8192313 were associated with increased susceptibility to TB, P=0.024 and P=0.045, respectively. However, these two P-values were not significant following Bonferroni correction. In all samples, the haplotype [CGA], representing three SFTPC variants, was revealed to increase the risk of TB (P=0.001 and P=0.005, following Bonferroni correction). Furthermore, patients with the AA genotype for rs1124 and with the CC genotype for rs8192313 were associated with higher levels of C-reactive protein (P=0.001 and P=0.005, respectively). The results of the present study indicated that the SFTPC SNPs may increase the susceptibility to TB and the immune response of the host to Mycobacterium tuberculosis and may potentially be novel biomarkers for the pathogenesis of TB.