Alagille syndrome is a genetic condition that causes liver problems, heart defects, and unique facial features. Liver disease in Alagille syndrome mainly affects the bile ducts, which are passage ways between the liver and the gallbladder that carry a substance that helps break down fat (bile). In Alagille syndrome, there are either not enough bile ducts (bile duct paucity) or the bile ducts are too narrow. These abnormalities lead to a buildup of bile, which damages the liver. Symptoms of liver damage include a yellowish color to the skin and white parts of the eyes (jaundice) and itchy skin. The most common heart defect in Alagille syndrome is a decrease in the blood flow from the heart to the lungs (pulmonic stenosis). Facial features include a broad forehead, deep set eyes, and a small pointed chin. Symptoms of Alagille syndrome vary in severity from one affected person to another, even in the same family.
Most cases of Alagille syndrome (97%) are caused by a mutation in the JAG1 gene, while a few cases are caused by a mutation in the NOTCH2 gene. These genes act as instructions to make proteins that are important for development. Alagille syndrome is inherited in an autosomal dominant manner, which means a mutation in just one of the two gene copies a person has is enough to cause the condition.
The diagnosis of Alagille syndrome is considered in children who have bile duct abnormalities, a heart defect and unusual facial features. Genetic testing is used to officially confirm the diagnosis. Treatment options include medications or surgeries to help the liver function. In severe cases, a liver transplant may be needed. If your child has been diagnosed with Alagille syndrome, discuss treatment options with their doctor. A genetic counselor may be helpful to further discuss the diagnosis. Support groups are available as resources for more information and to connect with other families affected by Alagille syndrome.