Overview
Omenn syndrome is a rare and very serious immune system disorder that affects babies, usually appearing in the first weeks or months of life. It belongs to a group of conditions called severe combined immunodeficiency (SCID), which means the body cannot properly fight infections. In Omenn syndrome, the immune system is not only weak — it also becomes overactive in a harmful way, attacking the body's own tissues. This happens because a small number of abnormal immune cells (called T cells) grow out of control and cause widespread inflammation. Babies with Omenn syndrome typically develop a red, scaly rash covering much of the body, along with enlarged lymph nodes, an enlarged liver and spleen, and chronic diarrhea. They are extremely vulnerable to serious infections from bacteria, viruses, and fungi. The condition is also sometimes called Omenn's syndrome or reticuloendotheliosis with eosinophilia. Without treatment, Omenn syndrome is life-threatening. The only known cure is a stem cell transplant (also called a bone marrow transplant), which replaces the faulty immune system with a healthy one. Before transplant, babies need careful medical support including antibiotics, antifungal medicines, and sometimes immune-suppressing drugs to control the harmful inflammation. Early diagnosis and transplant give the best chance of survival and a healthy life.
Also known as:
Key symptoms:
Widespread red, scaly skin rash (erythroderma) covering much of the bodySwollen lymph nodes throughout the bodyEnlarged liver and spleenChronic, severe diarrheaFailure to gain weight or grow normallyRecurrent and severe infections (bacterial, viral, fungal)High levels of a type of immune cell called eosinophils in the bloodVery high levels of a protein called IgE in the bloodLow or absent levels of other protective antibodies (IgG, IgA, IgM)Hair loss (alopecia)Fluid buildup causing swelling (edema)Fever that keeps coming backExtreme tiredness and poor feeding in infants
Clinical phenotype terms (28)— 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)
Treatments
No FDA-approved treatments are currently listed for Omenn syndrome.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for Omenn syndrome 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 Omenn syndrome.
Community
No community posts yet. Be the first to share your experience with Omenn syndrome.
Start the conversation →Latest news about Omenn syndrome
No recent news articles for Omenn syndrome.
Follow this condition to be notified when news becomes available.
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.Which gene mutation is causing my child's Omenn syndrome, and what does that mean for treatment options?,How quickly do we need to find a stem cell donor, and what types of donors are suitable?,What infections should we be most worried about right now, and how are we protecting against them?,What are the chances of a successful transplant, and what does recovery look like?,Should other family members be tested for the same gene mutations?,Are there any clinical trials or gene therapy studies my child might be eligible for?,What long-term monitoring will my child need after a successful transplant?
Common questions about Omenn syndrome
What is Omenn syndrome?
Omenn syndrome is a rare and very serious immune system disorder that affects babies, usually appearing in the first weeks or months of life. It belongs to a group of conditions called severe combined immunodeficiency (SCID), which means the body cannot properly fight infections. In Omenn syndrome, the immune system is not only weak — it also becomes overactive in a harmful way, attacking the body's own tissues. This happens because a small number of abnormal immune cells (called T cells) grow out of control and cause widespread inflammation. Babies with Omenn syndrome typically develop a red
How is Omenn syndrome inherited?
Omenn syndrome follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Omenn syndrome typically begin?
Typical onset of Omenn syndrome is neonatal. Age of onset can vary across affected individuals.
Which specialists treat Omenn syndrome?
3 specialists and care centers treating Omenn syndrome are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.