The groups ‘Intermediate crucial biomarkers’ contained genes played important roles in H-I disease related biological processes: CXCL8 (shared), HBG2, GRIN2A, and FGFBP1 (PAH - specific), FAM111B (HAPC - specific), C12orf39 and SLAMF1 (PE - specific). The gene discussed is HBG2; the disease is pulmonary arterial hypertension.