Crigler-Najjar syndrome is a rare genetic condition characterized by high levels of a toxic substance called bilirubin in the blood (hyperbilirubinemia).
Crigler-Najjar syndrome can affect anyone, as it is a genetic condition.
Crigler-Najjar syndrome is divided into two types. Type 1 (CN1) is very severe, and affected individuals can die in childhood due to kernicterus, although with proper treatment, they may survive longer. Type 2 (CN2) is less severe. People with CN2 are less likely to develop kernicterus, and most affected individuals survive into adulthood.
Crigler-Najjar syndrome is caused by mutations in the UGT1A1 gene. This gene creates enzymes in the liver that break down bilirubin to remove it from the body. Bilirubin – a yellow substance produced when red blood cells are broken down which is removed from the body only after it undergoes a chemical reaction in the liver, which converts the toxic form of bilirubin (called unconjugated bilirubin) to a nontoxic form called conjugated bilirubin.
Symptoms of Crigler-Najjar syndrome range in severity based on the type. Newborns with Crigler-Najjar syndrome will experience persistent jaundice, where they have a yellow tint to their skin and eyes beyond the newborn period. People with Crigler-Najjar syndrome have a buildup of unconjugated bilirubin in their blood (unconjugated hyperbilirubinemia).
The laboratory diagnosis of Crigler-Najjar syndrome is by blood tests which include Liver Function Tests, complete blood count and bilirubin tests. Crigler-Najjar syndrome can be treated with phototherapy, medications, plasmapheresis and liver transplant.
