Summary about Disease
Crigler-Najjar syndrome (CNS) is a rare, inherited disorder that affects the liver's ability to process bilirubin, a yellow pigment produced during the normal breakdown of red blood cells. This leads to hyperbilirubinemia (high levels of bilirubin in the blood), causing jaundice (yellowing of the skin and eyes) and potential neurological damage if left untreated. There are two main types: Type I is more severe, characterized by a complete or near-complete absence of the enzyme needed to process bilirubin; Type II is less severe, with some enzyme activity present.
Symptoms
The primary symptom is jaundice, which appears very early in life (often within the first few days). Other symptoms can include:
Dark urine
Pale stools
Lethargy
Poor feeding
Neurological damage (kernicterus) in severe cases (Type I), leading to developmental delays, movement problems, and hearing loss.
Causes
Crigler-Najjar syndrome is caused by mutations in the UGT1A1 gene. This gene provides instructions for making an enzyme called UDP-glucuronosyltransferase 1A1. This enzyme is responsible for glucuronidation, a process that attaches glucuronic acid to bilirubin. This modification makes bilirubin water-soluble so it can be excreted from the body. Mutations in the *UGT1A1* gene lead to a deficiency or complete absence of this enzyme, preventing the efficient removal of bilirubin. The condition is inherited in an autosomal recessive pattern, meaning both parents must carry a copy of the mutated gene for a child to be affected.
Medicine Used
Phototherapy: Exposure to blue light helps break down bilirubin in the skin. It is a primary treatment, especially in newborns.
Exchange Transfusion: Used in severe cases, particularly in newborns, to rapidly lower bilirubin levels.
Phenobarbital: Used in Type II Crigler-Najjar syndrome to induce UGT1A1 gene expression and increase enzyme activity. It is not effective in Type I.
Liver Transplantation: The only cure for Type I Crigler-Najjar syndrome.
Is Communicable
No, Crigler-Najjar syndrome is not communicable. It is a genetic disorder and cannot be spread from person to person.
Precautions
Genetic Counseling: Families with a history of Crigler-Najjar syndrome should seek genetic counseling to understand the risk of passing the condition to their children.
Monitoring Bilirubin Levels: Regular monitoring of bilirubin levels is crucial for managing the condition and preventing complications.
Adherence to Treatment: Strict adherence to prescribed phototherapy or other treatments is essential.
Avoidance of Certain Medications: Certain medications can interfere with bilirubin metabolism and should be avoided. Consult with a doctor.
How long does an outbreak last?
Crigler-Najjar syndrome is not an "outbreak". It's a chronic condition present from birth. Jaundice will persist unless treated. Without treatment, hyperbilirubinemia and its effects are continuous.
How is it diagnosed?
Diagnosis is based on:
Clinical Examination: Observing jaundice and other symptoms.
Bilirubin Levels: Measuring elevated unconjugated bilirubin levels in the blood.
Liver Function Tests: Assessing liver function.
Genetic Testing: Confirming mutations in the UGT1A1 gene.
Liver Biopsy: Can be used, especially to determine the type of Crigler-Najjar Syndrome, assessing UGT1A1 enzyme activity, but is less common with the availability of genetic testing.
Timeline of Symptoms
Newborn Period: Jaundice appears within the first few days of life.
Infancy/Childhood (Untreated Type I): Severe jaundice persists, leading to potential neurological damage (kernicterus) within weeks or months.
Type II: Jaundice may be less severe and may fluctuate, potentially worsening during illness or stress.
Lifelong (Without Treatment): Chronic hyperbilirubinemia persists, requiring ongoing management or liver transplantation in Type I.
Important Considerations
Early diagnosis and treatment are critical to prevent neurological damage.
Type I Crigler-Najjar syndrome often requires lifelong phototherapy or liver transplantation.
Type II Crigler-Najjar syndrome may be managed with phenobarbital and intermittent phototherapy.
Regular monitoring of bilirubin levels is essential.
Neurological assessments are necessary to detect and manage kernicterus.
Supportive care is important for families dealing with this chronic condition.