We made a minireview on the association of many candidate genes with TB based on recent research studies systematically, such as the human leukocyte antigen (HLA) gene, the solute carrier family 11 member 1 (SLC11A1) gene system, the vitamin D receptor (VDR) gene, the mannan-binding lectin (MBL) gene, the nitric oxide synthase 2A (NOS2A) gene, the speckled 110 (SP110) gene, and the P2X7 receptor (P2X7) gene.
Moreover, some studies have shown that serum MBL levels were influenced by the MBL-2 gene polymorphisms and that it plays an important role in tuberculosis infection.
The objective of this study is to compare the frequency of TNF-alpha and MBL gene polymorphisms between patients diagnosed with tuberculosis and healthy volunteers in Turkey, and determine the association between tuberculosis and TNF-alpha gene (G308A) and MBL2 gene codon 54 polymorphisms.
In conclusion, MBL2rs1800450 and rs1800451 polymorphisms play a protective role in TB infection and reinforce their critical significance as a potential genetic marker for TB resistance.
Both genotype GC at rs7096206 of MBL genes and genotype TC at rs2273346 and rs6695096 of MASP-2 genes were more prevalent in the TB patient group than the healthy control group (P<0.05, OR 1.393, 1.302 and 1.426 respectively).
Many genes involved in tuberculosis susceptibility (e.g., NRAMP1 (SLC11A1), IFNG, NOS2A, VDR, ISG15, TACO, TLR1, TLR, IL18R1, chemokines, PADI, DUSP14, MBL, and MASP-2) have been subjected to epigenetic modification.
Diplotype LXPA/HYPA, producer of high levels of MBL, was significantly more frequent in HHC than in patients (16.8% vs. 6.4%, P = 0.031) suggesting a protective role against the development of TB disease that has not been previously found.
Genotype CG at rs7096206 of MBL genes (OR 2.02) and genotype TC at rs6695096 of MASP-2 genes (OR 1.67) were more prevalent in the TB patients than in healthy controls (p<0.05).
The YA/YA diplotype, which exhibited high plasma MBL levels, was associated with protection against active TB in younger patients (mean age = 32)≦ 45 years old (odds ratio, 0.61; 95% confidence interval, 0.46-0.80).
The present study suggests that mannose-binding lectin can protect against TB or predispose the host to the disease depending on the haplotype pair of the host.
The distribution of allele and genotype frequencies varied little among the different groups, and it was not possible to establish any clear association between the variants of the MBL2 gene and the susceptibility to or clinical profile of tuberculosis infections in the population analyzed.
Polymorphisms in human leukocyte antigen (HLA), MBL2, CD209, vitamin D receptor, cytokine, chemokine and chemokine receptor genes have been shown to be associated with development of TB in HIV patients.
Several important candidate genes like human leucocyte antigen/alleles and non-human leucocyte antigen genes, such as cytokines and their receptors, chemokines and their receptors, pattern recognition receptors (including toll-like receptors, mannose binding lectin and the dendritic cell-specific intercellular adhesion molecule-3 grabbing nonintegrin), solute carrier family 11A member 1 (formerly known as natural resistance-associated macrophage protein 1) and purinergic P2X7 receptor gene polymorphisms, have been associated with differential susceptibility to TB in various ethnic populations.
While this may indicate that high MBL levels protect against infection with TB, the increase was also of a degree consistent with the acute-phase reaction.