A significant difference was found in serum levels of Gal-9 between patients with RP-ILD (n = 20) and patients with non-RP-ILD (n = 36) [42.4 (34.9–68.5) vs. 26.4 (17.0–39.8) ng/mL, p < 0.001] (Figure 2A). This evidence concerns the gene LGALS9 and interstitial lung disease.