Primary Immunodeficiency Disease (PIDD)

• Primary immunodeficiency disease (PIDD) is a disease of the immune system itself, in contrast to secondary immunodeficiency with a weak immune system as a result of another condition, like HIV/AIDS.
• There are hundreds of different types of primary immunodeficiency disease.
• Most types of primary immunodeficiency disease are due to inherited (genetic) defects, so there is no known way to prevent primary immunodeficiency disease.
• Primary immunodeficiency disease is most often diagnosed in infants and children, although the signs and symptoms may sometimes first appear in later childhood or adulthood.
• Signs and symptoms of primary immunodeficiency disease include severe or recurrent infections such as pneumonia, sinus infections, abscesses, ear infections, or skin infections.
• Blood tests to measure immune cell counts, antibodies, and other substances important for immune function are key to making the diagnosis of primary immunodeficiency disease.
• Treatments for primary immunodeficiency disease include antibiotics to fight infection and depending upon the cause of the primary immunodeficiency disease, immune-boosting therapies.
• Stem cell transplantation may be an appropriate treatment for severe or life-threatening types of primary immunodeficiency disease.

Primary immunodeficiency disease (PIDD) is a condition in which the immune system is weaker than normal. The term "primary" implies that there is an independent problem of the immune system rather than a weakening of the immune system due to another condition like HIV/AIDS (a secondary immune deficiency).

Primary immunodeficiency disease is most often identified in infants and children, but it is possible that the condition is identified in adulthood. Primary immunodeficiency disease represents a diverse group of hundreds of diseases that can weaken the immune system.

Most often, primary immunodeficiency disease results in increased susceptibility to both acute and chronic (long-term) infections.

Primary immunodeficiency disease is a group of multiple different diseases. In fact, the World Health Organization (WHO) recognizes over 250 diseases that lead to primary immunodeficiency. The conditions that are immune deficient can include problems with antibody formation, problems with cell-mediated immune response, or innate immune system disorders.

The types of primary immunodeficiency disease are far too numerous to list here. Examples of some of the more commonly known primary immunodeficiency diseases include:

• Wiscott-Aldrich syndrome
• Severe combined immunodeficiency disease (SCID)
• DiGeorge syndrome
• Ataxia-telangectasia
• Chronic granulomatous disease
• Transient hypogammaglobulinemia of infancy
• Agammaglobulinemia
• Complement deficiencies
• Selective IgA deficiency

Most primary immunodeficiency diseases are inherited, meaning that there is a gene defect present at birth that leads to the condition. As such, the condition usually is seen in infants or children. Sometimes, however, the condition may not become apparent until late childhood or even adulthood.

Many of the specific forms of primary immunodeficiency disease will have symptoms and signs specific to that condition, but in general, PIDDs are characterized by frequent infections. In particular, symptoms and signs suggestive of primary immunodeficiency disease can include:

• Frequent or hard-to-treat infections
• Recurrent pneumonia, sinus infections, or ear infections
• Weight loss or delayed growth
• Enlarged lymph nodes
• Enlarged spleen
• Recurrent deep abscesses in internal organs
• Recurrent skin abscesses
• Digestive problems, including nausea, diarrhea, or abdominal cramping
• Abnormal blood counts

Most cases of PIDD are genetic, inherited diseases.

Immunologists are scientists or doctors who specialize in diseases of the immune system. Immunologist physicians may manage the treatment of patients with primary immunodeficiency disease. Infectious disease specialists are also frequently involved in the care of these patients. Depending on the exact cause of primary immunodeficiency disease, other specialists may be consulted, including neurologists, hematologists, rheumatologists, internal medicine specialists, cardiologists, pulmonologists, gastroenterologists, and others.

Any patient suspected of having a primary immunodeficiency disease will undergo a thorough medical examination. Blood tests are typically done to make the diagnosis. Blood tests are done to check for immune cell counts as well as levels of antibodies and other substances necessary for a functioning immune system. DNA testing may be done to identify a specific genetic defect.

In families with a known history of primary immunodeficiency disease, prenatal testing may be done to detect genetic problems in the developing fetus.

To treat recurrent infections antibiotics, antiviral medications, and antifungal drugs may be used. These medications may be stronger than those used to treat infections in people with a normally functioning immune system and may need to be administered intravenously (IV). Sometimes, long-term antibiotics are given to prevent the development of infections.

To boost the immune system: The treatment for primary immunodeficiency disease depends upon the specific defect that is causing the immune system to malfunction. Examples of immune system treatments include:

• Intravenous or subcutaneous immunoglobulins to provide antibodies to fight infection
• Growth factor therapy if immune function deficiency is due to lack of certain immune cells
• Gamma interferon therapy involves administering a synthetic interferon (a substance that strengthens the immune system). This treatment is used for patients with chronic granulomatous disease.

Stem cell transplantation can be used to replace the defective immune system in patients with severe or life-threatening types of primary immunodeficiency disease. This requires a stem cell donor that is a biologic match to the patient. Typically, the patient's immune system is destroyed via chemotherapy and/or radiation therapy, and the normal stem cells are transferred to the patient. Stem cell transplantation has a number of risks and is not always successful, but it can offer some patients with primary immunodeficiency disease a permanent cure.

You can help your child with primary immunodeficiency disease by learning as much about the condition as possible, and helping your child through any challenges he or she may face. Many patients and families find it helpful to talk to another affected family or participate in a support group (support groups).

You also can help your child take steps to avoid as many infections as possible, including

• good hygiene practices,
• avoiding exposure to contagious illness, and
• ensuring that he or she receives all appropriate childhood, adolescent, and adult vaccinations.

Maintaining a healthy diet and getting adequate exercise and sleep also can help the body fight infections.

Because most cases of primary immunodeficiency disease result from an inherited gene defect, there is no way to prevent their occurrence.

Because primary immunodeficiency disease represents a group of hundreds of different diseases, it is not possible to assign a prognosis to this group of conditions in general. Many children and adults with primary immunodeficiency disease can attend school or work and maintain productive lives.

The Immune Deficiency Foundation offers a number of support and educational resources, including peer support programs. Your treatment center or care team may also have information about specific support programs in your area.