Alagille syndrome is a genetic condition that results in various symptoms in different parts of the body, including the liver. A person with Alagille syndrome has fewer than the normal number of small bile ducts inside the liver. The liver is the organ in the abdomen—the area between the chest and hips—that makes blood proteins and bile, stores energy and nutrients, fights infection, and removes harmful chemicals from the blood.
Bile ducts are tubes that carry bile from the liver cells to the gallbladder for storage and to the small intestine for use in digestion. Bile is fluid made by the liver that carries toxins and waste products out of the body and helps the body digest fats and the fat-soluble vitamins A, D, E, and K. In people with Alagille syndrome, the decreased number of bile ducts causes bile to build up in the liver, a condition also called cholestasis, leading to liver damage and liver disease.