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Alagille syndrome is an inherited condition that causes a lower than normal number of small bile ducts inside the liver.
Bile ducts are also known as hepatic ducts. These are tubes that carry bile from the liver cells to the gallbladder from where the bile is drained off into the intestines.
Bile is produced in the liver by the degradation of the red blood cells and has two major functions – to remove toxins and wastes away from the body and to help in digestion of fats and the fat-soluble vitamins A, D, E, and K.
In Alagile syndrome there are a decreased number of hepatic ducts that leads to accumulation of bile in the liver. Eventually the liver may stop working and this may necessitate a liver transplant.
As bile builds up in the liver causing damage, other organs may also be affected. This includes heart, kidneys, blood vessels, bones and eyes.
Alagile syndrome occurs in about one in every 70,000 births and is seen at equal rates in both males and females. The symptoms appear before the baby completes two years.
Alagille syndrome is inherited as an autosomal dominant trait. This means it can be inherited from one parent who has the disorder. Children who have one parent with the disorder are 50 percent likely to develop the disorder.
Those with the disorder have a genetic mutation in the Jagged1 (JAG1) gene. Mutations in the NOTCH2 gene may also be seen in less than 1% sufferers.
The symptoms of Alagille syndrome vary according to the severity of the condition. They may vary between sufferers in the same family as well.
Babies with Alagille syndrome may manifest liver symptoms within the first few weeks of life. These symptoms can also occur in children and adults with the condition. The liver symptoms include:-
Because of its rare incidence and varying symptoms, it may be difficult to diagnose Alagille syndrome. Laboratory tests including blood tests to check liver function and nutritional status are prescribed first. Usually high levels of bilirubin are detected.
An abdominal ultrasound is performed to detect liver enlargement and state of the bile ducts. To confirm the condition a liver biopsy is advised. This checks the decreased number of hepatic ducts.
Other organ systems are also evaluated. This includes checking the heart, eyes, kidneys etc. An X ray of the spine is performed to check for deformities.
Genetic tests may be advised to confirm the diagnosis. The JAG1 gene mutation alone may be diagnostic of the condition. If there are no symptoms along with the mutation, the person may be refereed for genetic counselling.
Treatment of Alagille syndrome aims at increasing the flow of bile from the liver thereby allowing normal growth and development to return.
Ursodiol is the only drug approved by the U.S. Food and Drug Administration to increase bile flow. Excessive itching is resolved as the bile flow improves. To relieve itching medications like cholestyramine, rifampin, naltrexone or antihistamines may be prescribed. Skin needs to be kept moisturized and hydrated.
Surgery is the next step. Partial external biliary diversion (PEBD) may provide better flow of bile and relieve itching. PEBD connects one end of the small intestine to the gallbladder and the other end to an opening in the abdomen by creating an artificial opening called stoma that allows bile to leave the body and get collected in a pouch. In severe cases of liver failure a liver transplant may be necessary.
The outlook or prognosis for people with Alagille syndrome depends on the severity of liver damage and associated problems.
Fifteen percent of people with Alagille syndrome will eventually require a liver transplant.
According to evidence around 75% of children diagnosed with Alagille syndrome live to at least 20 years of age with early nutritional, medical and surgical management.
Many adults with Alagille syndrome who improve with treatment lead normal, productive lives. Death is mainly caused by liver failure, heart problems and associated conditions.