Over 250 different primary immunodeficiencies (PIDs) have been identified, with about 20 of these accounting for over 90 per cent of cases. This means that many conditions are extremely rare: indeed for some conditions, fewer than ten cases have been identified.
Classification of PIDs
Every two years an international committee of experts meets to revise and update this classification, adding new conditions and information on the genes that cause PIDs.
At present, PIDs are grouped or classified under eight major subcategories based on what cells or parts of the immune system are affected.
These subcategories are:
- Combined immunodeficiencies including conditions such as X-linked severe combined immunodeficiency (X-SCID) and adenosine deaminase (ADA) deficiency.
- Well-defined syndromes with immunodeficiencyincluding conditions such as Wiskott–Aldrich syndrome(WAS) and DiGeorge syndrome.
- Predominantly antibody deficiencies including the conditions common variable immune deficiency (CVID) and selective IgA deficiency.
- Diseases of immune dysregulation including conditions such as Chediak–Higashi syndrome and X-linked lymphoproliferative syndrome (XLP).
- Congenital defects of phagocyte number, function, or both including disorders such as chronic granulomatous disorder (CGD) and Barth syndrome.
- Defects in innate immunity including conditions such as NEMO deficiency.
- Autoinflammatory disorders such as Muckle–Wells syndrome and Blau syndrome.
- Complement deficiencies
Click here for the Codes of the various deficiencies