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Updated on March 18, 2025
Primary immunodeficiency (PI) refers to a group of rare genetic conditions where the immune system is unable to effectively protect the body from infections or other diseases. This makes a person with PI more susceptible to infections that are severe, difficult to treat, and uncommon. It also puts a person at greater risk for certain types of cancer and other diseases.
PI is caused by genetic variations (genetic mutations or abnormalities). In many cases, these variations are inherited, passed on through the genetics of a person's biological parents. Some occur sporadically, meaning a genetic change is not inherited but occurs for another reason. In some cases, the genetics are not fully understood—but research is ongoing.
There are hundreds of different types of PI. More are being identified due to improvements in technologies that can closely examine DNA and identify genetic mutations.
PI affects people of all ages. In some cases, PI is identified in early childhood. In other cases, it may not be diagnosed until a person has reached adulthood. One type, severe combined immunodeficiency (SCID) is screened for in newborns in the United States. Prenatal screening may be done for specific types of PI if there is a known family history.
Challenges of PI in children
As a caregiver of a child with signs and symptoms of PI, your pediatrician will likely refer you to an immunologist, a healthcare provider who specializes in treating disorders of the immune system. An immunologist can order blood tests and genetic testing to diagnose PI and identify the type of PI.
Children with PI and caregivers may face a number of challenges including:
- Delays in growth and development
- Frequent absences from school due to infections
- Emotional and social challenges, such as feeling different from peers, fears about infections and hospitalizations, and lower self esteem
- Stress related to making healthcare decisions, paying for treatment, and administering treatments
- The impact on family, such as adapting to new routines and infection prevention measures, additional responsibilities, stress, and caregiver burnout
Establishing a good working relationship with a healthcare provider is essential to successful treatment. Your provider can help you understand what safety precautions you need to take for school and other activities. A healthcare provider can also guide you in explaining and educating a child with PI about their condition.
Treating PI in children
Immunoglobulin (Ig) replacement therapy is a mainstay of treatment at any age. This involves infusions of antibodies that help the immune system function. Intravenous infusions (IVIg) will be given by a healthcare provider. As a caregiver, you may also be trained to administer subcutaneous infusions (SCIg) at home.
Preventing and addressing infections will be a focus of treatment. This will include precautions like careful hygiene practices. At times, it can include antibiotic, antiviral, or antifungal medications to treat or prevent infections.
For severe cases of PI in children, treatments such as hematopoietic stem cell transplantation (HSCT) might be considered. This is an intense procedure that involves chemotherapy and requires a matched donor, but it has the potential to cure PI, and children are often better candidates than adults. Gene therapies are a new and emerging treatment for some types of PI, and may also be something you discuss with a child's healthcare team.
Treatment for PI can change as a person approaches adulthood. Your healthcare team can guide you on how to help your child take more responsibility for their care as they grow older.
