The cause of biliary atresia is not known. The two types of biliary atresia appear to be a “fetal” form, which arises during fetal life and is present at the time of birth, and a “perinatal” form, which is more typical and does not become evident until the second to fourth week of life. Some children, particularly those with the fetal form of biliary atresia, often have other birth defects in the heart, spleen, or intestines.

An important fact is that biliary atresia is not an inherited disease. Cases of biliary atresia do not run in families. Identical twins have been born with only one child having the disease.

Biliary atresia is most likely caused by an event occurring during fetal life or around the time of birth. Possibilities for the “triggering” event may include one or a combination of the following factors:

• Infection with a virus or bacterium.
• A problem with the immune system.
• An abnormal bile component.
• An error in development of the liver and bile ducts.

Research on the cause of biliary atresia is of great importance. Progress in the management and prevention of biliary atresia can only come from a better understanding of its cause or causes.

Source: digestive.niddk.nih.gov