Further, class I HDACs (HDAC1, HDAC2, HDAC3, and HDAC8) were screened in the cardiopulmonary tissues and PAAFs of IPAH patients and healthy donors, and a consistently elevated expression of HDAC1 and HDAC8 in IPAH-PAs and IPAH-PAAFs was reported [64]. The gene discussed is HDAC1; the disease is idiopathic pulmonary arterial hypertension.