Nonetheless, further validation of the clinical applicability of HDGF in an appropriate cohort is warranted.54, 53 In addition to HDGF, in a study by Nikolic et al, plasma bone morphogenetic protein-9 emerged as a differentiative biomarker of PoPH among patients with liver disease, other PAH and PH etiologies, as well as a predictor of transplant-free survival in PAH.32 The gene discussed is HDGF; the disease is pulmonary arterial hypertension.