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. The gene discussed is TET3; the disease is pulmonary arterial hypertension.