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What are primary immunodeficiency diseases?

Primary immunodeficiency diseases (PIDD) are a group of more than 350 rare, chronic disorders in which part of the body’s immune system is absent or functions abnormally. These diseases are caused by genetic defects that are often hereditary. Some PIDD are detected at birth or in early childhood, but they can be found in individuals of any age or gender. Some PIDD affect a single part of the immune system, while others may affect more than one component of the immune system. While PIDD differ, they all share one common feature: each is caused by a defect in one of the functions of the body's normal immune system.


Because one of the most important functions of the normal immune system is to protect against infection, patients with PIDD commonly have an increased susceptibility of infection. These infections may be in the skin, sinuses, throat, ears, lungs, brain or spinal cord, or in the urinary and intestinal tracts. Individuals with PIDD are at an increased risk of infection and endure recurrent health problems, including serious and debilitating illnesses. Other symptoms of PIDD may include weight loss, chronic diseases such as immune thrombocytopenia, hemolytic anemia, vitiligo, neutropenia or pernicious anemia. 

You should be suspicious that you may have a PIDD if you have:

  • Severe infections that requires hospitalization/intravenous antibiotics
  • Persistent infections that don’t completely clear up or clears very slowly
  • Unusual infections caused by an uncommon bacteria or virus
  • Recurrent infections that keep coming back or if this runs in the family
  • If you have multiple autoimmune diseases
  • If you have an unusual malignancy or multiple cancers
  • If you’re allergic symptoms are severe and unresponsive to standard allergy medications

Proper diagnosis is key

Symptoms of PIDD are often mistaken for other common illnesses by patients, families and healthcare professionals. If PIDD is not properly diagnosed, it can lead to more serious chronic illnesses and permanent hearing, sight, neurologic and lung function deficits, and even death. Patients with primary immunodeficiency can also develop allergic, autoimmune or malignant diseases. Proper diagnosis of PIDD is important because with proper medical care and immune reconstitution, most patients can live full and independent lives.

Our approach to diagnosis and treatment

At the Jeffrey Modell Diagnostic and Treatment Center, we provide comprehensive immunology testing of PIDD in infants, children, adolescents and adults. Before your first appointment, you will fill out a complete medical history and symptom sheet, so that we can be fully prepared for your visit. Your physician will run any necessary tests to help establish a definitive diagnoses. Our Center includes a basic and clinical science laboratory that can help diagnose various forms of PIDD.

Our clinical immunology subspecialists work closely with research scientists in the Division of Allergy and Immunology to make the diagnosis of PIDD and determine how immune reconstitution is progressing. The collaborative team develops individualized therapeutic plans to seamlessly treat patients with PIDD.

Our advanced treatment options include:

  • Antibody (immunoglobulin) replacement therapy, given intravenously or subcutaneously
  • Stem cell transplantation for T-cell or combined T- and B-cell deficiency diseases
  • Supportive antimicrobial treatment protocols
  • NIH and industry sponsored clinical trials that provide investigative cutting-edge treatment protocols for the various forms of PIDD

Our Center especially excels at treating severe combined immunodeficiency (SCID), a serious and potentially life threatening PIDD. All babies born in Queens and Nassau Counties with an abnormal newborn screen for SCID are referred by the New York State Department of Health to our Center for evaluation, establishment of a diagnosis and treatment as needed.