The 6 genes (RETN, KLK1, CXCL5, HP, PID1 and CXCL3) that showed statistically significant differences in qPCR analysis (TB vs. LTBI, TB vs. HCs, P < 0.05) were further validated in an additional independent sample set, which included 66 TB patients, 78 LTBI individuals and 86 HCs (Table 2). The gene discussed is KLK1; the disease is tuberculosis.