In SSc patients, there were no significant differences in endothelin-1 concentrations between those with limited and diffuse cutaneous SSc (10 studies; SMD = 0.32, 95% CI -0.07 to 0.71 <i>P</i> = .11; very low certainty), and with and without digital ulcers (5 studies; SMD = 0.82, 95% CI -0.06 to 1.69, <i>P</i> = .066; very low certainty), pulmonary arterial hypertension (7 studies; SMD = 0.22, 95% CI -0.01 to 0.45, <i>P</i> = .066; very low certainty) or interstitial lung disease (3 studies; SMD = 0.09, 95% CI -0.18 to 0.35, <i>P</i> = .51; very low certainty). This evidence concerns the gene EDN1 and interstitial lung disease.