Among these proteins, Caveolin-1, filamin A expression, and cathepsin D were significantly upregulated, and glutathione-transferase MU1 (GSTM1) was significantly downregulated in the irreversible PAH-CHD group; the expression of Caveolin-1, filamin A, and cathepsin D were positively correlated with whereas the expression of GSTM1 was negatively correlated with pathological grade. The gene discussed is CTSD; the disease is pulmonary arterial hypertension.