Alagille syndrome is an autosomal dominant, multisystem disorder that frequently involves the liver, classically characterized by bile duct paucity on pathology, and is caused by mutations in Jagged1 (JAG1) or Notch2. Ductal plate malformations refer to cholangiopathies associated with the lack of normal development and remodeling of the intrahepatic bile ducts that occurs along the branches of the developing portal vein. Here, JAG1 is linked to Alagille syndrome.