Introduction: Vitamin D levels and genetic factors, vitamin D receptor (VDR) and Toll like receptor- 2 (TLR-2) gene single nucleotide polymorphisms (SNPs), determine susceptibility to pulmonary tuberculosis. We aimed to evaluate vitamin D deficiency, VDR and TLR-2 gene SNPs in tuberculous meningitis (TBM).
Methods: This case-control study included 130 subjects each in three arms (TBM, pulmonary tuberculosis and healthy control). This study was performed in a large tertiary care institution of North India. Subjects were enrolled from August 2013 to July 2015. Vitamin D levels were measured using enzyme immunoassay. SNPs in VDR and TLR-2 gene were assessed using polymerase chain reaction-sequencing method. TBM patients were followed for 6 months.
Results: Vitamin D deficiency was significantly more common in TBM compared to controls and pulmonary tuberculosis (TBM versus controls p < 0.001; TBM versus pulmonary tuberculosis p < 0.001). The heterozygous (TC) and mutant (CC) genotypes of Taq1 VDR SNP were significantly associated with TBM as compared to controls [TC; p < 0.001, odds ratio (OR) = 3.53 (1.95-6.40); CC; p = 0.002 OR = 5.97 (1.89-18.84)]. The heterozygous genotypes were significantly associated with TBM as compared with pulmonary tuberculosis [p = 0.001; OR = 2.53(1.43-4.45)]. Heterozygous (TG) and mutants (GG) forms of Apa1 VDR SNPs were significantly associated with TBM compared to controls [TG; p = 0.001, OR = 2.86 (1.58-5.17), GG; p = 0.002, OR = 5.11 (1.80-14.54)] and pulmonary tuberculosis. There was no significant difference in the frequency of TLR-2 SNPs. No association was found between outcome of TBM and vitamin D deficiency, VDR or TLR-2 SNPs.
Conclusion: Vitamin D deficiency and VDR polymorphisms are associated with the susceptibility of TBM.
Keywords: Single nucleotide polymorphisms; Toll like receptor 2; Vitamin D; Vitamin D receptor.