Adult-Onset Alagille Syndrome Presenting With Recurrent Cholestasis: A Rare Genetic Diagnosis Confirmed by Whole Exome Sequencing.

Alagille syndrome, also known as arteriohepatic dysplasia, is a multisystem genetic disorder inherited in an autosomal dominant pattern. It is primarily caused by mutations in the Jagged canonical Notch ligand 1 (JAG1) gene and is classically diagnosed in childhood with cholestasis due to bile duct paucity. Adult presentation is rare owing to its incomplete penetrance and milder phenotypes. We report a case of a 33-year-old male with recurrent cholestasis and no prior history of childhood jaundice. Common acquired etiologies were excluded, and comprehensive evaluation revealed a JAG1 mutation by whole exome sequencing (WES). Multiorgan screening showed no extrahepatic involvement. Treatment with ursodeoxycholic acid (UDCA) and supportive therapy led to clinical and biochemical resolution. This case emphasizes the significance of considering rare genetic disorders in adults with unexplained recurrent cholestasis and highlights the value of molecular diagnostics such as whole exome sequencing in facilitating timely diagnosis.