Alagille syndrome (ALGS) is a rare genetic condition affecting different parts of the body, such as the liver, kidneys, and heart. Lifestyle changes, medications, and surgery can help manage the condition.

ALGS affects a person’s bile ducts. The liver secretes bile and bile ducts carry it from the liver to the gallbladder. Bile helps aid digestion in the small intestine.

A person who has ALGS may have fewer or malformed bile ducts. This can lead to their liver transferring less bile to the gallbladder. Over time, a buildup of bile in the liver may cause liver damage.

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ALGS is a condition that causes a person to have fewer functioning bile ducts. This may result in less bile flowing from the liver to the gallbladder, resulting in bile building up inside the liver and can lead to liver scarring and damage.

The National Institute for Diabetes and Digestive and Kidney Diseases (NIDDK) notes ALGS may also affect other parts of a person’s body, such as the:

  • heart
  • face
  • eyes
  • kidneys
  • skeleton
  • blood vessels

ALGS is a genetic condition. This means it occurs due to an alteration in a person’s genes. Genetic conditions are present from birth.

The condition’s name derives from French hepatologist Dr. Daniel Alagille, who discovered the condition in 1969. Other names for the condition include:

  • arteriohepatic dysplasia
  • syndromic bile duct paucity
  • Alagille-Watson syndrome
  • Watson-Miller syndrome

ALGS occurs due to a genetic alteration. Evidence notes that the majority of ALGS occurrences are due to a variation in a person’s JAG1 gene. However, an alteration in the NOTCH2 gene may cause ALGS in roughly 2.5% of people, and around 3.2% of people have an unknown gene variation.

A person may inherit a genetic condition from their parents. A person has a 50% chance of developing ALGS if they have a parent with the condition. However, the NIDDK notes that sporadic gene variations cause ALGS in around 50% to 70% of people. These refer to alterations a person does not inherit. Instead, natural cell processes cause alterations to occur.

ALGS occurs in no more than around 1 in every 30,000 live births.

Some people with ALGS may experience mild symptoms. Other people may have severe symptoms or develop life threatening complications. The NIDDK notes symptoms may also vary within family members who have the condition.

A reduction in bile leaving the liver — which some health experts call cholestasis — causes the most common symptoms of ALGS, which include:

  • severe skin itchiness
  • yellowing of the skin and whites of the eyes
  • dark-colored urine
  • light-colored stools
  • yellow bumps of fat in the skin
  • loose, greasy, foul-smelling stool
  • an enlarged liver or spleen

These signs generally develop within the first year of an infant’s life.

ALGS is a multisystem condition that can cause symptoms throughout the body. These may include:

  • poor growth and energy
  • heart problems, such as a heart murmur or heart defect
  • white or light gray rings around the cornea, which is the outer layer of the eye
  • a wide forehead and pointed chin and nose
  • butterfly vertebrae, which is where the bones in the spine have a butterfly shape
  • narrowing and weakness in the blood vessels, especially those of the neck and head
  • kidney problems

There are various methods a doctor may use to diagnose a person with ALGS. These may include a physical exam to look for signs of ALGS, such as yellow skin or eye symptoms.

A doctor may diagnose a person with ALGS if they have signs of the condition affecting the following areas of the body:

A doctor may also ask a person about their medical and family history, including any family history of liver problems. Additionally, a doctor may perform an eye exam or take a tissue sample from a person’s liver.

Additional tests a doctor may use to diagnose a person with ALGS include the following.

Laboratory tests

A doctor may use the following tests to check a person for ALGS:

  • blood tests to check liver function, cholesterol levels, and fat-soluble vitamin levels
  • genetic testing to check for gene mutations that may cause ALGS
  • urine testing to look for signs of kidney problems

Imaging tests

A doctor may use certain imaging tests to look for internal signs of ALGS. These may include:

The treatment for Alagille syndrome will typically vary depending on a person’s specific symptoms. Often, it may involve the coordinated efforts of a team of specialists. This may include pediatricians, gastroenterologists, cardiologists, ophthalmologists, and other healthcare professionals.

A doctor may prescribe certain medications to treat a person’s ALGS symptoms. These may include ursodiol, which helps improve bile flow from the liver. To help reduce itching, they may also prescribe medications, such as cholestyramine or antihistamines.

If medications do not improve a person’s symptoms, a doctor may recommend surgery. This may include a partial biliary diversion, which uses a small part of the bowel to divert bile acids, or a liver transplant.

A doctor may also recommend a person make certain changes to their diet. This may help improve bone issues or problems with growth.

ALGS may cause a person to develop certain health complications. The NIDDK notes these may include:

Alagille syndrome (ALGS) is a genetic condition that may affect many areas of the body. It typically occurs due to variations in the JAG1 gene and causes a person to have fewer or less functional bile ducts. Bile ducts are tubes that carry bile from the liver and gallbladder, through the pancreas, and into the small intestine.

Liver symptoms are generally the first sign of ALGS. These generally develop before an infant is a year old. A person may experience mild symptoms with ALGS or they may develop life threatening complications.

The treatment for ALGS may depend on a person’s symptoms. It may involve a combination of lifestyle changes and medications. For people with more severe cases, surgery may be necessary. If a person notices signs of ALGS in an infant, they should contact a doctor.