Using a discovery cohort of 38 control and 74 IPF patients that were approximately age and sex matched, we found significantly higher GDF15 in IPF patients compared with controls (Fig. 6A; 1,918 pg/mL versus 420 pg/mL, P < 0.0001, Welch’s t test). The gene discussed is GDF15; the disease is idiopathic pulmonary fibrosis.