Patients with both initial serum KL-6 >/= 1000 U/mL and serial increase in serum KL-6 had the steepest decline, suggesting a role for KL-6 predicting a worse lung functional status [15], and thus indirectly associated with increased risk of exacerbations, since reduced lung function is a risk factor for AE-IPF. This evidence concerns the gene MUC1 and idiopathic pulmonary fibrosis.