What is primary immunodeficiency disease (PIDD)?

Primary immunodeficiency refers to a group of more than 100 disorders affecting one or more parts of the immune system. Primary immunodeficiency is also called primary immunodeficiency disease or disorder (or PIDD). They prevent the immune system from functioning properly. They make you more susceptible to infection and certain diseases.

PIDD results from genetic mutations (changes) that are usually inherited, or passed down, within families. Treatment focuses on preventing and managing infections and replacing missing or defective immune system components.

Who is likely to have primary immunodeficiency disease (PIDD)?

Anyone can develop PIDD. In most cases, primary immune deficiencies develop before age 20. PIDD is more common in men.

What causes primary immunodeficiency disease (PIDD)?

PIDD results from genetic mutations affecting one or several components of the immune system, including cells and proteins. These mutations may cause parts of the immune system to be:

  • Present in lesser quantities than normal.
  • Defective.
  • Totally absent.

In 50-60 percent of cases, PIDD relates to defects in B lymphocytes (B cells). These immune system cells make antibodies, specific proteins in the body. The immune system uses antibodies to destroy pathogens (disease-causing agents) like bacteria or viruses.

What are the symptoms of primary immunodeficiency disease (PIDD)?

Having repeated or unusual infections that are difficult to treat are the first signs of PIDD for many people. Other signs suggesting primary immune deficiency may include:

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