Alagille syndrome (ALGS) is a rare, autosomal dominant disorder that affects multiple systems. It was first reported by Alagille et al in 1969 and further elaborated on its clinical, biochemical, and histological features in 1975. The main organs involved in the disease include the liver, heart, eyes, bones, and kidneys. As a rare genetic disease, ALGS is primarily observed in children, and confirmed cases in adults are rarely reported. Therefore, we report a case of an adult female who has been diagnosed with ALGS, and the genetic testing revealed a heterozygous mutation at position 933_934 of the Jagged 1 (JAG1) gene, which was discovered for the first time.