Common Causes Of Alagille Syndrome

Jagged1 Gene

Also called the JAG1, this gene creates a protein called Jagged-1, which goes through the cellular membrane and remains inside and outside of the cell. It can connect to proteins, or ligands, from other cells, carrying their messages on to the cell’s nucleus. Jagged-1 has an extracellular part that connects to the ligand, as well as an intracellular part that receives the message from the other cell and transports it to the nucleus. When there is a mutation with JAG1, therefore mutating the protein Jagged-1, messages from one cell to another are misread. When these messages are misinterpreted or unreceived, the cell’s original function can be damaged or lost completely, which is what happens in the liver in Alagille syndrome. Because of miscommunications between cells, the bile ducts are deformed or simply not there.

Scarring In The Liver

Scarring in the liver is caused by the bile ducts being malformed or nonexistent. Bile is unable to travel through the ducts into the duodenum, and it backs up into the liver. This bile build-up causes scarring and prevents the liver from working normally. When the liver is not functioning correctly, patients become jaundiced, which means they have a yellow tinge the whites of their eyes and their skin. Severely itchy skin is also a sign bile has built up in the liver. Malnutrition can also occur since bile is needed to break down fats before the body can absorb them. When fat cannot be broken down, fat-soluble vitamins cannot be absorbed resulting in a deficiency. A liver transplant may be needed for survival in extreme cases.