In short, the following aspects were considered: (1) there are fewer studies on the causal relationship of circulating CRP levels on the risk of IPF prevalence; (2) some contradictory results have emerged from these studies; (3) observational studies are likely to be affected by potential confounders or reverse causality bias that prevents reliable conclusions from being drawn. The gene discussed is CRP; the disease is idiopathic pulmonary fibrosis.