Overview
Immunodeficiency by defective expression of MHC class I, also known as MHC class I deficiency or Bare Lymphocyte Syndrome type I (BLS type I), is a rare inherited immune system disorder. In this condition, the body fails to properly display a set of proteins called MHC class I molecules on the surface of most cells. These proteins act like name tags that help the immune system tell the difference between the body's own healthy cells and foreign or infected cells. Without them, a key group of immune cells called CD8+ T cells (also called cytotoxic or 'killer' T cells) cannot develop or work properly. As a result, people with this condition have a weakened immune system that struggles to fight off certain infections, especially viruses and some bacteria. The lungs are often the most affected organ, and repeated respiratory infections are the hallmark of this disease. Unlike some other immune deficiencies, this condition tends to be milder than MHC class II deficiency, and some people may not be diagnosed until later in childhood or even adulthood. Treatment focuses on preventing and managing infections, often with long-term antibiotics and antiviral medicines. In severe cases, a stem cell transplant may be considered. Regular monitoring by an immunologist is essential to protect lung health and overall quality of life.
Also known as:
Key symptoms:
Repeated lung infections (pneumonia, bronchitis)Chronic coughShortness of breathSinusitis (sinus infections)Skin infectionsSlow growth or failure to thrive in childrenFatigue and low energyEar infectionsBronchiectasis (permanent widening and scarring of the airways from repeated infections)Reduced number of CD8+ T cells in blood tests
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Variable
Can begin at different ages, from infancy through adulthood
Treatments
No FDA-approved treatments are currently listed for Immunodeficiency by defective expression of MHC class I.
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Specialists
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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
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Caregiver Resources
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Mental Health Support
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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 genes should be tested in my child and our family, and what do the results mean for other family members?,What infections should I be most worried about, and what are the warning signs I should act on immediately?,Should my child receive preventive antibiotics, and if so, for how long?,How often should lung function and imaging be checked to monitor for damage?,Is a stem cell transplant an option for my child, and what are the risks and benefits?,Are there any clinical trials or research studies we could participate in?,What vaccinations are safe, and which ones should be avoided?
Common questions about Immunodeficiency by defective expression of MHC class I
What is Immunodeficiency by defective expression of MHC class I?
Immunodeficiency by defective expression of MHC class I, also known as MHC class I deficiency or Bare Lymphocyte Syndrome type I (BLS type I), is a rare inherited immune system disorder. In this condition, the body fails to properly display a set of proteins called MHC class I molecules on the surface of most cells. These proteins act like name tags that help the immune system tell the difference between the body's own healthy cells and foreign or infected cells. Without them, a key group of immune cells called CD8+ T cells (also called cytotoxic or 'killer' T cells) cannot develop or work pro
How is Immunodeficiency by defective expression of MHC class I inherited?
Immunodeficiency by defective expression of MHC class I follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.