Study of the correlation between NRAMP1 gene polymorphisms and susceptibility to tuberculosis in Tibetan people in Qinghai
Objective 
To investigate the correlation between NRAMP1 gene polymorphisms and susceptibility to tuberculosis (TB) in Tibetan people in Qinghai. 
 
 
Methods 
A case-control study was conducted in this study, involving 99 Tibetan patients with TB and 89 healthy Tibetans. The single nucleotide polymorphisms of NRAMP1 gene at rs17235409 and rs3731865 sites were detected by using TaqMan probe method. Gene cloning and sequencing typing were performed to analyze the single nucleotide polymorphisms of NRAMP1 gene at the rs17235416 site. SPASS20.0 software was used to statistically analyze the correlation between NRAMP1 gene polymorphisms and susceptibility to TB in Tibetan people. 
 
 
Results 
No significant difference in the genotype frequencies of rs3731865 and rs17235409 was found between the two groups (χ2=0.852, P=0.356; χ2=0.279, P=0.597). The genotype frequencies of TGTG/TGTG and TGTG/del+ del/del at the rs17235416 site were 70.7% (70/99) and 29.3% (29/99) in patients with TB and 86.5% (77/89) and 13.5% (12/89) in healthy subjects. There were significant differences in the genotype frequencies of TGTG/TGTG and TGTG/del+ del/del between the two groups (χ2=6.870, P=0.009). The genotypes of TGTG/del and del/del at rs17235416 were risk factors for TB (OR=0.376; 95%CI: 0.178-1.794 as compared with the TGTG/TGTG genotype in Tibetan people in Qinghai. 
 
 
Conclusion 
This study suggested that the NRAMP1 gene polymorphisms at rs3731865 and rs1723409 sites had no correlation with the susceptibility to TB in Tibetans in Qinghai. However, the NRAMP1 gene polymorphisms at rs17235416 site were correlated with the susceptibility to TB. The TGTG/del alleles at the rs17235416 site might be the risk factors for tuberculosis in Tibetans in Qinghai. 
 
 
Key words: 
Tibetan; NRAMP1 gene polymorphism; Tuberculosis; Macrophage