Common Causes Of Alagille Syndrome

Alagille syndrome, affecting multiple systems in the body, is a relatively rare, genetic disease typically diagnosed in babies or young children. Symptoms can be life-threatening requiring organ transplants, or they can be nonexistent. Usually resulting in liver damage, it can also cause a hole between the lower ventricles of the heart, which hinders blood flow from the heart to the lungs. Facial features commonly associated with Alagille syndrome include a broad forehead, deep-set eyes, and small chin. It is caused by a mutation of the Jagged1 gene (JAG1). This gene plays a vital role in the body in cell to cell communications during development. The mutation in JAG1 is usually passed down from parent to child in an autosomal dominant fashion.

Autosomal Dominant Inheritance

Alagille syndrome is caused by autosomal dominant inheritance. Humans have twenty-three pairs of chromosomes containing specific genetic coding found in genes, and autosomal genes are in pairs on chromosomes numbered one through twenty-two. One gene is from the mother, and one is from the father. In dominant inheritance, only one copy of a mutated gene from either parent is needed to cause the disorder, but if the second copy of the same gene is normal, the mutated copy will dominate. This mutation for Alagille syndrome is found on chromosome 20 and particularly with the gene called Jagged1, which is in charge of cell to cell communication during embryonic development. This communication is important in determining what organ or tissue the cells will become. Because of the mutation to this gene, communications between cells are mixed or lost completely.

Continue reading to learn more about the common causes of Alagille syndrome.