HAS1 and ulcerative colitis: ROC analysis revealed additional proteins with potentially good discriminatory power for pinpointing possible patients suffering from PSC disease (Figure 2), and among them, nicotinamide phosphoribosyltransferase (R = 0.515, p = 0.020) and hyaluronan synthase 1 (R = 0.531, p = 0.016) are also positively correlated with the presence of ulcerative colitis.