Wang et al. examined the expression level of DNMT1 by immunohistochemistry staining in PDAs, benign pancreatic tissues, and PDA precursor lesions (pancreatic intraepithelial neoplasia (PanINs) and intraductal papillary mucinous neoplasm (IPMN)), and found that DNMT1 expression levels increased from benign tissue to precursor lesions to PDA [26]. This evidence concerns the gene DNMT1 and Patent ductus arteriosus.