Association of polymorphisms in the collagen region of human SP-A1 and SP-A2 genes with pulmonary tuberculosis in Indian population.

Surfactant protein A (SP-A) binds to and modulates phagocytosis of Mycobacterium tuberculosis by macrophages. We investigated the relationship between polymorphisms in the collagen regions of SP-A1 and SP-A2 genes and pulmonary tuberculosis. In the present study, seven single nucleotide polymorphisms (SNPs) (4 exonic and 3 intronic) have been identified in the collagen regions of SP-A1 and SP-A2 genes in Indian population. Two intronic polymorphisms, SP-A1C1416T ((p = 0.0000, odds ratio (OR) = 20.767,95% CI: 8.315-OR<51.870) and SP-A2C1382G (p = 0.0054; OR = 3.675, 95% CI: 1.400< OR<9.644), showed significant association with pulmonary tuberculosis (number of patients = 10, number of controls = 7). A redundant SNPA1660G of SP-A2gene showed significant association with pulmonary tuberculosis (number of patients = 17, number of controls = 19, p = 0.0000, OR = 8.94,95% CI: 3.311<OR<24.126). This polymorphism, when existing along with a non-redundant polymorphism, SP-A2G1649C (Ala91Pro) resulted in a stronger association with pulmonary tuberculosis (number of patients = 17, number of controls = 19, p = 0.000, OR = 16.3, 95% CI: 7.8644<OR<33.9244). The results indicated that these SNPs in the collagen region of SP-A2 may be one of the contributing factors to the genetic predisposition to pulmonary tuberculosis.