Although nitrate, sulfate and ET‐1 tended to be higher in SSc patients, no significant differences between groups were observed in baseline levels of NO‐derived species (nitrate: P = 0.23; nitrite: P = 0.88; RXNO: P = 0.88, Fig. 4), ET‐1 (P = 0.24, Fig. 5) and sulfate (P = 0.14, Fig. 6). The gene discussed is EDN1; the disease is systemic sclerosis.