To verify the expression differences of hub genes IL-7R, LCK, and HDAC1 between SSc and SSc-PAH, we used GSE22356 and GSE33463 as test sets and GSE19617 as the validation set, which included 21 SSc patients and 15 SSc-PAH patients. The gene discussed is HDAC1; the disease is pulmonary arterial hypertension.