Our data confirm and extend the abovementioned observations, suggesting that RDW may predict the presence of PAH in CTD patients; moreover, RDW has a potential prognostic implication, given its association with sPAP, right ventricular size, and DLCO, which are well-known prognostic markers in SSc-related PAH [21, 22]. This evidence concerns the gene PDZK1IP1 and pulmonary arterial hypertension.