As shown in Figure 4A,B, following prenatal PAH exposure, the expression of DNA methyltransferases (DNA methyltransferase 1 (Dnmt1), DNA methyltransferase 3A (Dnmt3a), and DNA methyltransferase 3B (Dnmt3b)) was increased, whereas the Tet3 expression was decreased. This evidence concerns the gene DNMT1 and pulmonary arterial hypertension.