PDCD1 and tuberculosis: Guo et al. [24] performed an analysis of the association between PD-1 gene and the risk of TB in the Chinese Han population and observed significant associations between SNPs of rs2227981 and rs2227982 sites in PD-1 gene and pulmonary TB susceptibility and clinical features, while some conflicting results were achieved by Li et al. [25], who reported that SNPs of rs2227981, rs11568821 and rs10204525 were not associated with susceptibility to TB in Xinjiang Uygur TB patients.