22q11.2 deletion syndrome (22q11DS aka DiGeorge syndrome), the genetic disorder caused by the deletion of a small part of chromosome 22, affects multiple systems in the body, including the immune system. Individuals with 22q11DS often face recurrent respiratory infections, immunodeficiency, and challenges related to vaccines due to immune dysfunction.
Recurrent Respiratory Problems
A hallmark of 22q11DS is thymic hypoplasia, which results in a reduced number of functional T cells. The thymus is essential for T cell development, and its underdevelopment impairs the immune response, making individuals with 22q11DS more vulnerable to infections, especially respiratory ones like pneumonia and bronchitis. In addition to T cell defects, B cell function can be impaired, leading to difficulties in producing antibodies. This combination of immune deficiencies increases susceptibility to infections and complicates their management.
Immunological Issues
The immune system in 22q11DS can be compromised, primarily due to thymic underdevelopment.
This leads to:
- T cell Deficiency: Reduced numbers of T cells, particularly CD4+ T cells, impair the body's ability to mount effective immune responses.
- Increased Infection Risk: The weakened immune system results in heightened vulnerability to infections, including viral, bacterial, and fungal respiratory infections
- Autoimmunity and Allergies: Some individuals may also experience autoimmune disorders or allergies due to immune system dysregulation.
-Other Immune Defects: Impaired B cell and NK cell function further contribute to immune challenges.
Vaccination Considerations
Vaccination is crucial for individuals with 22q11DS, given their increased susceptibility to infections, especially respiratory illnesses. However, their immune system may not respond as robustly to vaccines, requiring special considerations:
- Live Attenuated Vaccines: Live vaccines, such as the MMR (measles, mumps, rubella) and rotavirus vaccines, may pose risks due to the compromised immune system. These vaccines might need to be avoided or postponed.
- Inactivated and Recombinant Vaccines: Non-live vaccines like the flu vaccine, Tdap (tetanus, diphtheria, and pertussis), and pneumococcal vaccines are generally safe and important for preventing respiratory infections.
- Pneumococcal and Influenza Vaccines: Pneumonia and flu are common and severe issues for individuals with 22q11DS. These vaccines are essential for reducing infection risk.
- Vaccine Response Monitoring: Individuals with 22q11DS may have a weaker immune response to vaccines. Blood tests may be used to monitor vaccine effectiveness, and booster doses may be required for adequate protection.
- Vaccination of Close Contacts: Ensuring that family members and caregivers are vaccinated is crucial to prevent the transmission of infections to individuals with 22q11DS.