ABSTRACT
BACKGROUND AND OBJECTIVES: Genetic factors are reported to be connected with tuberculosis (TB) infection. Studies have shown that genetic variations in genes involved in the vitamin D pathway influence the levels of vitamin D found in the bloodstream (serum). Cyp27b1 (1α-hydroxylase) is an enzyme that activates the synthesis of bioactive vitamin D3 by hydroxylation of 25(OH)D3.The in vitro studies reported rare gene variants of Cyp27b1 such as rs118204011 and rs118204012, associated with loss of Cyp27b1 function and lower serum vitamin D levels. Globally, a critical gap exists in understanding the link between these gene variants with TB and vitamin D levels. Hence, the study objective is to comprehend the association of Cyp27b1 rs118204009 (G/A), rs118204011 (C/T), and rs118204012 (A/G) with tuberculosis susceptibility/protection and to assess the influence of gene variants on vitamin D levels in both healthy controls (HCs) and those with pulmonary tuberculosis (PTB) in South India. METHODS: Genomic DNA extraction was performed by salting-out procedure and subsequently genotyped through polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. Vitamin D level was measured by Enzyme-Linked Immunosorbent Assay (ELISA). RESULTS: In rs118204012 (A/G), a substantial association was found with PTB susceptibility in allele 'A' [Odds Ratio (OR): 1.52 (1.02-2.26); p = 0.044] and 'AA' genotype [OR: 1.69 (1.02-2.81); p = 0.040] through the dominant model. Allele 'G' [OR: 0.66 (0.44-0.98); p = 0.044) was found to be associated with protection against TB. Males were associated with increased susceptibility towards TB compared to females in the rs118204011 "CC" [OR: 3.94 (1.94-7.98); p = 0.002] and rs118204012 'AA' [OR: 4.57 (2.13-9.79); p = 0.0001] genotypes. Vitamin D insufficiency (<30 ng/ml) was more prevalent in PTB patients (66.67 %) with the rs118201012 'AA' genotype compared with healthy controls (57.14 %). This genotype was associated with disease susceptible odds ratio of 1.5. CONCLUSION: Cyp27b1 rs118204012 'AA' genotype was found to have association with vitamin D insufficiency and TB susceptibility. In terms of gender, our findings suggest that male individuals are correlated with a higher TB risk. This suggest that the gene variants may be involved in the downstream processing of serum Vitamin D levels and its association with the disease.
