However, the obstructive characteristics develop in a time-dependent manner (Figure 3) and also occur in Alagille syndrome, A1ATd, cystic fibrosis, parenteral nutrition-associated NC (PNALD), PFIC3, and isolated neonatal sclerosing cholangitis (gene DCDC2) [43]. The gene discussed is ABCB4; the disease is Alagille syndrome.