We observed that serum KL-6 values were significantly higher in patients with specific CTD-ILD, including PM (1097.0 vs 454.7 μg/ml, P < 0.001), SSc (823.7 vs 485.2 μg/ml, P = 0.0028), and UCTD (690.6 vs 330.5 μg/ml, P = 0.038) (Figure 1B). Here, MUC1 is linked to systemic sclerosis.