Overview
Crigler-Najjar syndrome type 2 (also called Arias syndrome) is a rare inherited liver disorder that affects how the body processes bilirubin. Bilirubin is a yellow substance made when red blood cells break down. Normally, the liver converts bilirubin into a form that can leave the body through bile. In Crigler-Najjar type 2, the liver enzyme responsible for this process — called UGT1A1 — works very poorly but not completely. This means bilirubin builds up in the blood, causing a yellow coloring of the skin and eyes called jaundice. Unlike the more severe type 1 form of this condition, people with Crigler-Najjar type 2 usually have moderately elevated bilirubin levels and a much better outlook. Most people live relatively normal lives, though they need ongoing monitoring. In some cases, especially during illness, fasting, or stress, bilirubin levels can rise high enough to cause serious problems, including brain damage (a condition called kernicterus or bilirubin encephalopathy). The main treatment is phototherapy — spending time under special blue lights that help break down bilirubin in the skin. A medication called phenobarbital can also help lower bilirubin levels in type 2 patients, which is an important difference from type 1. Liver transplant can be curative but is rarely needed for type 2. With proper management, most people with Crigler-Najjar type 2 do well long-term.
Also known as:
Key symptoms:
Yellow skin and eyes (jaundice) present from birth or early infancyElevated bilirubin levels in the bloodYellowing that may worsen during illness, fasting, or stressFatigue or low energy during bilirubin spikesIn severe or untreated cases: confusion, difficulty concentrating, or neurological symptoms from bilirubin affecting the brainPossible hearing problems if bilirubin levels have been very highNo other obvious liver disease symptoms in most casesGenerally normal growth and development with treatment
Clinical phenotype terms (3)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
FDA & Trial Timeline
2 eventsFederal State Budget Institution Research Center for Obstetrics, Gynecology and Perinatology Ministry of Healthcare — PHASE1
Azienda Sanitaria Universitaria Friuli Centrale — NA
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Crigler-Najjar syndrome type 2.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for Crigler-Najjar syndrome type 2 at this time.
New trials open frequently. Follow this disease to get notified.
Rare Disease Specialist
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Crigler-Najjar syndrome type 2.
Community
No community posts yet. Be the first to share your experience with Crigler-Najjar syndrome type 2.
Start the conversation →Latest news about Crigler-Najjar syndrome type 2
Disease timeline:
New recruiting trial: Perineal Massage in Pregnancy to Reduce the Levator Ani Coactivation
A new clinical trial is recruiting patients for Crigler-Najjar syndrome type 2
New trial: Gene Therapy for Crigler Najjar Syndrome Type I (AlphaCN)
Phase PHASE1 trial recruiting. GT-UGT1A1-AAV8-02
Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What bilirubin level is safe for my child, and at what level should I seek emergency care?,Should my child take phenobarbital every day, and what are the side effects?,What triggers can raise bilirubin levels, and how do we manage them at home?,Does my child need phototherapy now, and how often might they need it in the future?,What is the long-term risk of brain damage, and how do we prevent it?,Should other family members be tested for this condition?,Are there any clinical trials or new treatments we should know about?
Common questions about Crigler-Najjar syndrome type 2
What is Crigler-Najjar syndrome type 2?
Crigler-Najjar syndrome type 2 (also called Arias syndrome) is a rare inherited liver disorder that affects how the body processes bilirubin. Bilirubin is a yellow substance made when red blood cells break down. Normally, the liver converts bilirubin into a form that can leave the body through bile. In Crigler-Najjar type 2, the liver enzyme responsible for this process — called UGT1A1 — works very poorly but not completely. This means bilirubin builds up in the blood, causing a yellow coloring of the skin and eyes called jaundice. Unlike the more severe type 1 form of this condition, people
How is Crigler-Najjar syndrome type 2 inherited?
Crigler-Najjar syndrome type 2 follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Crigler-Najjar syndrome type 2 typically begin?
Typical onset of Crigler-Najjar syndrome type 2 is neonatal. Age of onset can vary across affected individuals.
Which specialists treat Crigler-Najjar syndrome type 2?
3 specialists and care centers treating Crigler-Najjar syndrome type 2 are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.