It is of note that the FL-OPN levels did not show any significant differences between multidrug-resistant (MDR) TB and non-MDR TB, whereas Ud-OPN was significantly (p = 0.0227) lower in MDR TB compared with non-MDR TB, suggesting that FL-OPN and Ud-OPN reflect different pathologies of TB [106]. This evidence concerns the gene SPP1 and tuberculosis.