What is Crigler-Najjar Syndrome?

Crigler-Najjar syndrome is an uncommon genetic condition in which a person's blood contains abnormally high bilirubin levels due to the lack of a particular metabolizing enzyme. High bilirubin levels lead to jaundice and can potentially cause severe brain damage. Doctors recognize two types of the disorder, with type one being the more severe and likelier to cause immediate health problems in a newborn. Type one also is very difficult to treat and is ultimately fatal in most cases. Type two Crigler-Najjar syndrome can usually be managed with regular medications.

Genetic research has shown that Crigler-Najjar syndrome is an autosomal recessive disorder, meaning that both parents must carry a copy of a particular mutated gene in order for it to be passed down to offspring. The defective gene is unable to produce sufficient quantities of an enzyme called uridine diphosphate glycosyltransferase (UGT). UGT normally metabolizes bilirubin, a substance that is produced when the liver breaks down used blood cells. Without enough UGT, bilirubin continuously builds up in the bloodstream.

Excess bilirubin leads to the appearance of jaundice, a yellowish tint to the skin and eyes. In type one Crigler-Najjar syndrome, jaundice is apparent shortly after birth. Left untreated, type one can quickly cause permanent brain damage. Individuals with type two may not develop jaundice until late childhood or adolescence. Type two patients are at much a lower risk of cognitive impairment.

X-rays, blood tests, and liver screenings are performed right away on a jaundiced newborn to check for an underlying cause. A specialist first attempts to identify more common causes of jaundice, such as reactions to breast milk and liver disorders. If blood and liver tests are inconclusive, genetic tests are performed to check for Crigler-Najjar syndrome. After making a diagnosis of type one or type two, the doctor can determine the best course of treatment.

Patients who have type two Crigler-Najjar syndrome are typically prescribed a medication called phenobarbital that helps prevent neurological complications. Often, no other treatment is necessary for type two, and patients simply need to receive regular checkups to ensure their conditions do not worsen. Babies with severe cases of type one may need to receive emergency blood transfusions or liver transplants to prevent fatal complications.

An infant often undergoes several transfusions and experimental light therapy sessions throughout the first few months of life to promote stable bilirubin levels. If initial treatment efforts are successful, it is possible for a patient to survive until early adulthood. The disease is fatal in almost all cases, however, as persistent jaundice eventually causes irreversible brain damage.