In most patients with Alagille syndrome (~94%) a mutation can be identified in the gene JAG1. Mutation types can vary but they all result in the cell not having enough JAG1protein to function correctly. This could be because a protein is made that is incorrect and the cell degrades it or it could be because a protein is made that is incorrect, which causes it not to function properly. JAG1 is a protein that sits on the cell surface and binds to a Notch receptor, activating a series of cellular events. When these do not happen, the characteristics abnormalities in the affected organs occur.
JAG1