Children's Hospital Colorado

Alagille Syndrome

What is Alagille syndrome?

Alagille syndrome is a genetic disorder, meaning that it is caused by a missing or mutated piece of deoxyribonucleic acid (DNA). DNA is the substance that makes up our genetic code, which provides the body with a blueprint for how to develop and function.

Specifically, Alagille syndrome is caused by the deletion or mutation of the JAG1 or NOTCH2 gene, which results in the body forming an insufficient number of bile ducts in the liver. Bile is the substance the body makes to help remove waste; when the body does not have enough bile ducts, bile can back up in the liver, causing liver disease and other complications.

In addition to a low number of bile ducts, we also associate Alagille syndrome with these conditions:

  • Unique facial structure
  • Heart abnormalities
  • Butterfly-shaped vertebrae
  • Kidney abnormalities
  • Blood vessel abnormalities
  • Posterior embryotoxon (an abnormally thick line bordering the eye’s iris)
  • Short stature

Who gets Alagille syndrome?

About 40% of newborns with Alagille syndrome have inherited it from a parent, while about 60% are born with a gene mutation that was not passed down from either parent. Alagille syndrome affects boys and girls of all races the same. It occurs in about one out of every 30,000 live births.