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What is PI?

Primary immunodeficiencies (PIs) are a group of more than 450 rare, chronic conditions where a part of the body’s immune system is missing or does not function correctly.

All primary immunodeficiencies are different, but they all disrupt the body’s immune system. They are also known as inborn errors of immunity (IEI).

What are the signs of a primary immunodeficiency?

PI conditions prevent the immune system from working as it should, so the body has a hard time protecting itself against infection. This increased susceptibility can lead to infections that are:

  • Recurrent (keep coming back).
  • Persistent (won’t completely clear up or clear very slowly).
  • Unusual (caused by an uncommon organism).
  • Severe (require hospitalization or intravenous antibiotics).
  • Shared by family members (others in your family have or have had a similar susceptibility to infection).

Keep in mind that infections can occur anywhere in the body, such as the brain or spinal cord, ears, lungs, skin, sinuses, throat, and urinary or intestinal tracts.

Additional symptoms of PIs include:

  • Swollen spleen, liver, or lymph nodes (splenomegaly, hepatomegaly, or lymphadenopathy).
  • Inflammation of blood vessels (vasculitis).
  • Autoimmune or autoinflammatory symptoms like inflammatory bowel disease.

If any of these phrases describe your symptoms, ask your doctor to check for the possibility of a primary immunodeficiency (PI). 

Who is at risk for PI?

PI conditions are caused by genetic variants and can affect anyone, regardless of age, gender, or ethnicity. Some PI disorders cause symptoms in infancy or early childhood, but others may not present until mid- or even older adulthood.

Autoimmunity in PI

Many times, abnormalities in the immune system that lead to PI also result in immune dysregulation. Autoimmune and autoinflammatory symptoms occur when the immune system is misdirected to attack normal parts of the body such as cells, tissues, or organs.

Learn about autoimmunity

“Always sick?” flyer

Use this printable flyer to raise awareness of PI in your community or share it with your healthcare provider if you think you may have PI.

“Always sick?” flyer

How well do you know your immune system?

Take our self-assessment to find out if your symptoms could point to a primary immunodeficiency (PI). It’s an informative way to gather insights that you can discuss with your healthcare provider.

Take our self-assessment
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Understand PI more clearly

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Diagnosis

Getting diagnosed is the first step toward effective treatment.

Learn how PI is diagnosed
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Treatment

With proper medical care and treatment, many people with PI are able to live healthy and independent lives.

Discover treatment options
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Types of PI

There are more than 450 primary immunodeficiencies with distinct definitions, causes, and symptoms.

Explore PI types
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The immune system and PI

To better understand PI, it's helpful to know more about how the immune system works.

Read about the immune system

Ask IDF

Getting answers can help create peace of mind. Ask us anything and we’ll consult with experts.

Submit a question

Do you have information to help me select a health insurance plan to cover my needs?

Selecting a health insurance plan can be a challenging process. Basic information to navigate insurance is available for the PI community.

Answers to specific questions, relative to cost and generally covered benefits, can be found by reviewing a plan’s summary of benefits, drug formulary list, provider network directory, and by contacting the insurance company. When speaking to an insurance representative, you should be able to receive answers to all of your questions. If not, ask to speak to someone who can answer them.

While this is often considered a tedious process, it is one of the most important steps you can take to ensure that a plan meets your needs. It is better to know everything you can about your plan before you select it than finding problems and hidden costs after you have made a decision. Please remember, it is okay to ask questions until you receive answers when communicating with insurance representatives.

I was just diagnosed; there’s so much information, where do I start?

We hear you! Your first, best step, is to set up an IDF account and subscribe to emails and/or text alerts. We’ll send you news and helpful resources, and you can change or cancel your subscription at any time. 

Next, download or order the IDF Patient & Family Handbook for Primary Immunodeficiency Diseases, Sixth Edition, which contains comprehensive information about the diagnosis, treatment, and management of primary immunodeficiency. 

If you have further questions or are diagnosed with PI and looking for more support, please reach out to us at 410-321-6647.

This page contains general medical and/or legal information that cannot be applied safely to any individual case. Medical and/or legal knowledge and practice can change rapidly. Therefore, this page should not be used as a substitute for professional medical and/or legal advice. Additionally, links to other resources and websites are shared for informational purposes only and should not be considered an endorsement by the Immune Deficiency Foundation.

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Immune Deficiency Foundation
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P: 410-321-6647

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