DNMT1 and pulmonary arterial hypertension: Accordingly, altered expression of miRNAs can cause pathogenic conditions such as PAH.35 In addition, emerging studies have shown that epigenetic modifications by DNA methylation and histone modification can also regulate the expression of miRNAs in a transcriptional manner, suggesting the therapeutic potential of HDAC and DNMT modulators for regulating miRNA expression for the treatment of PAH.9, 36