What type of mutation causes alagille syndrome?

Autosomal dominant: Alagille syndrome has an autsomal dominant genetic inheritance pattern. It is rare, however, and affects the heart and liver primarily. In 90% of cases, mutations on chromosome 20 that affect the JAG1 gene causes this syndrome. A few people have mutations in a gene called NOTCH2. Defects in these genes are thought to lead to abnormal embryonic development in the affected organs.