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Primary Immunodeficiency

Primary immunodeficiency—commonly referred to as PI but also referred to as PID and PIDD — is an umbrella term used to describe a group of more than 350 disorders that can cause your immune system to not work like it should. The immune system protects the body from germs like bacteria and viruses. So, if part of your immune system is not functioning properly, you’ll be more likely to get infections, and it may take you longer to recover. You may also have recurring infections and you may not respond to traditional antibiotic treatment.

Some of the more common types of PI include selective IgA deficiency, common variable immune deficiency (CVID), X-linked agammaglobulinemia (XLA), and severe combined immunodeficiency (SCID).

What causes Primary Immunodeficiency?

Primary immunodeficiency is not contagious. It cannot be passed from one person to another. It is usually inherited, which means it is passed down through families. Or it can be caused by errors in the genes of the cells that make up the immune system.

Cells of the Immune System

About primary immunodeficiency

Primary immunodeficiency was once thought to be very rare but it is now more common than originally thought. As PI awareness with physicians continues to grow, more people are getting diagnosed. In an Immune Deficiency Foundation (IDF) survey conducted in 2005, it was estimated that a quarter of a million people in the United States have been diagnosed with a PI, and many more have not yet been diagnosed—at least half a million people are affected by a PI, according to an estimate by the National Institutes of Health. More recent estimates suggest that six million people may be living with PI worldwide.

Primary immunodeficiency should not be confused with autoimmune disorders or secondary immunodeficiency. With an autoimmune disorder (like rheumatoid arthritis or Type 1 diabetes), the immune system gets confused and attacks the body.

How is primary immunodeficiency diagnosed?

Once thought to be a child’s disease, we now know that PI can be diagnosed at any age. Signs of PI can be seen early in a child’s life, but also may occur in older children, teenagers and adults. The effects of PI can vary in severity depending on the type of PI and susceptibility to different infections.

Increased susceptibility to recurrent infections is one of the most common symptoms of PI. However, the symptoms can vary, and they can be mistaken for common infections. This can make it difficult to diagnose PI. In fact, in a 2005 survey conducted by the Immune Deficiency Foundation (IDF), in which 1137 patients responded, the average time from onset of symptoms to diagnosis is estimated at 12.4 years.

Early diagnosis is important for early treatment. If left untreated, the frequent infections caused by PI can lead to organ damage, such as lung damage or permanent hearing loss. People whose PI is discovered later in life may already have some permanent organ damage from previous infections. Once a person is diagnosed, it is important to evaluate their family members as well. Immunoglobulin (Ig) replacement treatment cannot reverse any existing damage, but proper treatment can reduce the number of infections.

The IDF recommends you ask your physician to check for possible PI if you have an infection that is:

  • Severe - requires hospitalization or intravenous antibiotics
  • Persistent - won’t completely clear up or clears very slowly
  • Unusual - caused by an uncommon organism
  • Recurrent - keeps coming back
    or if it
  • Runs in the Family - others in your family have had a similar susceptibility to infection

Where can I find support?

If you or a loved one has been diagnosed with PI, you’re not alone. Connecting with others can give you a way to learn from people who have been where you are. Reach out and get involved!

Takeda provides funding to some of the below organizations in support of efforts that include, but are not limited to: research, education, meetings/events and support.


Explore the resources available through this wide network of healthcare professionals dedicated to improving the quality of patient care.


The mission of the Clinical Immunology Society is to facilitate education, translational research and novel approaches to therapy in clinical immunology to promote excellence in the care of patients with immunologic/inflammatory disorders.


The Immune Deficiency Foundation (IDF), founded in 1980, is the national nonprofit patient organization dedicated to improving the diagnosis, treatment and quality of life of persons with PI through advocacy, education and research.

Learn about primary immune deficiency (PI), how it's diagnosed, the types of PI, and the resources and support available.

Jeffrey Modell Foundation

The Jeffrey Modell Foundation (JMF) is an international, non-profit, organization dedicated to helping individuals and family members affected by primary immunodeficiency disorders. The foundation provides funding of research fellowships and laboratory facilities and is engaged in ongoing education campaigns to promote awareness of primary immune deficiency (PI).

National Organization for Rare Disorders (NORD)

A rare disease umbrella organization that provides advocacy, research, education and patient services in the US. See how they help and find out how you can get involved.

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