Moreover, McMahan et al. [83] found significantly increased plasma levels of PlGF and VEGF-receptor 1 (i.e., FLT-1, a decoy receptor that binds to free VEGF-A, VEGF-B and PlGF, thus downregulating their activity) in SSc patients complicated by PH vs. those in SSc patients without PAH, but no further information was given regarding the concentration of these biomarkers in the different PH subtypes in SSc. This evidence concerns the gene PGF and pulmonary arterial hypertension.