Alagille syndrome is a genetic disorder characterized by the abnormalities of the liver and other organs of the body. The common condition of this disorder includes the reduced bile flow from the liver as the result of only few bile ducts present within the liver. The progressive destruction of the bile ducts within the liver results in the scarring of the liver. This condition is usually differentiated from the other liver disease because of the other organs affected as well. This includes the spine, eyes, kidneys and the cardiovascular system. The severity of the syndrome varies with different individuals and can range from a mild condition to a more serious form. This syndrome is estimated to affect around 1 in 100,000 newborn infants.
Symptoms
The common condition associated with alagille syndrome includes the blockage of the bile from the liver causing liver damage. The initial symptoms include jaundice and poor growth rate of infants. The other symptoms may include itchy skin, fatty deposits on the skin, abnormal butterfly shape of the bones in the spinal cord, stunted growth and poor weight gain in children. They can also develop heart conditions with the problem of blood flow from the heart into the lungs, irregularities of the eyes and abnormal kidney function. The facial anomalies include a broad forehead, pointed chin and deep-set eyes. The blood vessels located within the brain and spinal cord can also become affected as the result of this condition.
Causes
This is inherited in an autosomal dominant pattern where one copy of the defective gene is sufficient to develop this syndrome. It is estimated that around 30 – 50% of the alagille syndrome cases are inherited. The other cases are the result of a new genetic mutation that occurs spontaneously with the sperm or the egg with no record of its prevalence in the family.
In the majority of the cases, the genetic mutation in the gene JAG1 is responsible for this syndrome. However, a small percentage of cases are presented with a mutation caused in another gene called NOTCH2. These genes are responsible for the production of certain proteins that trigger signaling system essential during the embryonic development. The genetic mutation disrupts the normal signaling system resulting in developmental errors that create the abnormal features associated with this syndrome.
Diagnosis
Although this condition is present at the birth of the infant, it may not be apparent until later in childhood. The individual’s medical history will also be evaluated along with a physical examination. Some of the tests that seek for abnormalities include eye examination, spine x-ray and chest exam to identify heart murmur. In some cases, a liver biopsy may be required to observe the liver tissue under the microscope to detect abnormalities.
Treatment
The treatment focuses on increasing the bile flow from the liver and to promote the healthy growth of the child. The medication helps increase the bile flow from the liver and to control the cholesterol levels in the blood. Children with this condition are required to consume a high-calorie diet as the result of their poor growth and their inability to absorb fat. A nutritional supplement with medium-chain triglycerides may be necessary as absorption is better with this type of fat. When the alagille syndrome severely affects the liver, a liver transplantation may be optional.
References
https://rarediseases.org/rare-diseases/alagille-syndrome/
https://ghr.nlm.nih.gov/condition/alagille-syndrome#diagnosis
http://www.chop.edu/conditions-diseases/alagille-syndrome#.V-1kPPl97IV
