Our findings indicate that serum miR-29a-3p, THBS2, and miR-29a-3p/THBS2 ratio exhibit diagnostic and prognostic values in patients with IPAH; in particular, their direct correlations with clinical parameters, such as mPAP, PVR, and TASPE, are promising in PAH. The gene discussed is THBS2; the disease is pulmonary arterial hypertension.