Based on the pyrosequencing results, higher DNA methylation levels were present at the CpG sites of BMPR2 in the VHD patients with mild PAH compared with the healthy controls, and even higher DNA methylation levels were observed at the CpG sites of BMPR2 in the VHD patients with moderate/severe PAH compared with the healthy controls (Figure 1B). This evidence concerns the gene BMPR2 and pulmonary arterial hypertension.