Primary Immunodeficiency Disease (PIDD)

About Primary Immunodeficiency Diseases

About Primary Immunodeficiency Diseases

What is PIDD?

Primary Immunodeficiency Diseases (PIDD) are a group of over 350 chronic disorders resulting from defects in the body's immune system that are caused by hereditary or genetic defects. PIDD patients have an increased susceptibility to infection due to their defective immune response, enduring recurrent health problems and often developing serious illnesses. With proper medical care, many patients can live full and independent lives.1, 2

Prevalence & Diagnosis

An estimated 1 in 1,200 people have a diagnosed PIDD. That is approximately 270,000 overall diagnosed cases in the US, which is similar to Leukemia. According to the National Institutes of Health, an additional 500,000 people in the US are undiagnosed.  The worldwide estimate is that 6 million people are living with PIDD.2,3 

PIDD can occur in individuals of any age. It is diagnosed by physical exam, family history, and laboratory testing after recurrent infections. It can also be diagnosed via newborn screening.  According to an IDF survey, it takes on average about 12 years for patients to receive a diagnosis of PIDD, from the time their symptoms begin.4  


One of the most common signs of primary immunodeficiency is frequent infections that are long lasting, or more difficult to treat than that of someone with a normal immune system. Patients may also get infections that a person with a healthy immune system likely would not get (opportunistic infections).1

Signs and symptoms differ depending on the type of primary immunodeficiency disorder, and they vary from person to person. 

Signs and symptoms can include:1

Frequent and recurrent infections such as pneumonia, bronchitis, sinus and/or ear infections, meningitis, skin infections and abscesses, viral, or fungal infections

Delayed growth and development

Chronic diarrhea with weight loss

Recurrent need for IV antibiotics

Recurrent abscesses

Family history of PIDD

PIDD Treatment Options

About Primary Immunodeficiency Diseases

There are several specific medical therapies available for people with PI with antibody deficiency that account for more than 50% of the primary immunodeficiencies. PIDD treatment options can be divided into three categories: immunoglobulin replacement therapy, stem cell therapy, and gene therapy.

Immunoglobulin Replacement Therapy

The term “immunoglobulin” (Ig) refers to the component of blood plasma that contains antibodies. These antibodies are used in the body to neutralize bacteria and viruses. Individuals who are unable to produce enough of these antibodies may benefit from Ig replacement therapy.1 

Immunoglobulin (Ig) replacement therapy is one of the most important and successful therapies for people with PIDD that affect antibody production. The therapy is both lifesaving and often lifelong, and it plays a huge role in the lives of many people with PI.

Ig given to people with PIDD partly replaces what the body should be making, but it does not stimulate the individual’s own immune system to make more Ig.  It replaces the missing antibodies, however, it does not correct the underlying defect in antibody production, making Ig replacement a lifelong therapy.1 

Ig replacement therapy is generally administered either intravenously (IVIg), or subcutaneously (SCIg). The Health care provider and patient or caregiver should discuss which route of administration is most appropriate for each patient.

Learn more about the differences between IVIg and SCIg


  1. Immune Deficiency Foundation. About Primary Immunodeficiencies. Accessed June 30, 2020
  2. National Institute of Allergy and Infectious Diseases. Primary immune deficiency diseases (PIDDs).   Accessed June 30, 2020
  3. Bousfiha et al. Primary Immunodeficiency Diseases Worldwide: More Common than Generally Thought. J Clin Immunol. 2013; 33:1-7
  4. Immune Deficiency Foundation. IDF Patient & Family Handbook for Primary Immunodeficiency Diseases, 6th Edition. 2019


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Jeffrey Modell Foundation

The Jeffrey Modell Foundation directs e‑orts toward early diagnosis, meaningful treatments, equal access to care, and ultimately, a cure for Primary Immunodeficiency.