As shown in Fig. 4, five hub genes (CDK1, SMC2, SMC4, KIF23 and CENPE) were further identified with significant increased expression in PAH patients compared to control (p = 0.00014 for CDK1, p = 1.1 × 10− 7 for SMC2, p = 6.5× 10− 8 for SMC4, p = 1.7× 10− 5 for KIF23, p = 2.9× 10− 7 for CENPE; Wilcoxon and Kruskal-Wallis test). The gene discussed is SMC4; the disease is pulmonary arterial hypertension.