In the ROC analysis, KL-6 and RF were significantly associated with a UIP pattern on HRCT and the optimal cut-off levels were 640 U/mL (C-index = 0.632, P = 0.046) and 88 IU/mL (C-index = 0.661, P = 0.015). This evidence concerns the gene MUC1 and idiopathic pulmonary fibrosis.