Rare Genetic Diseases an Overview of Alagille Syndrome

Alagille Syndrome is an inherited disorder that occurs in one out of every 70,000 births according to the National Digestive Diseases Information Clearinghouse. Usually, children receive a diagnosis before the age of three.


A common symptom of Alagille Syndrome is jaundice. As this disorder affects the liver, there is a build-up of bilirubin in the body. Many infants suffer from jaundice due to an immature liver. For these infants, the jaundice will clear in several weeks. For infants born with Alagille Syndrome, the jaundice will not clear.

The buildup of bilirubin in the body can lead to excessive itching called pruritis. The itching caused can be severe in certain individuals.

Bile is necessary for the correct absorption of food including fats and vitamins. Younger infants may not grow properly and older children may have a delay in the onset of puberty.

Damage to the Body

A person born with Alagille Syndrome will have less than the normal number of small bile ducts. Found in the liver, these tubes are responsible for carrying bile to the gallbladder. The lack of the ducts can lead to an increase in bile. Consequences of an increase in bile include liver failure and the eventual need for a liver transplant.


With such a few number of cases seen each year, Alagille Syndrome is often difficult to diagnose. Tests to diagnose the disease can include blood tests, ultrasounds, liver biopsies or a cardiology exam.

Further, doctors may perform genetic tests to look for a mutation in the JAG1 gene. Ninety-five percent of people with the syndrome have a mutation or error at this gene.

Offering parents genetic testing after a child’s diagnosis is common as Alagille Syndrome is an autosomal dominant disorder. This indicates that a child inherits he disease from at least one parent. If a parent has the disorder, each child will have a fifty percent chance of also being born with this rare disease.

After liver disease, a heart murmur is a common symptom. The presence of a heart murmur is used to distinguish Alagille Syndrome from other liver diseases. In most cases, the heart murmur does not cause any significant issues. In rare cases, there may be serious problems with the walls or valves of the heart.


With the decrease in bile flow due to the lack of ducts, increasing the flow is a standard treatment. There is currently only one drug on the market approved for this.

Other treatments focus on the various side effects the disorder causes, such as the extreme itching, rather than the syndrome itself.

Outlook after Diagnosis

Because the severity of the disease varies, so does the outcome after a diagnosis. A liver transplant is eventually required in fifteen percent of cases. Currently three-fourths of children will live to be twenty years old. Some adults lead normal lives. Liver failure or heart problems are the top causes of death with Alagille Syndrome.

Research continues on identifying the interaction of genes to clarify the causes of the disease. Further treatments are also being tested. See a doctor for more information about a specific diagnosis.