Immune system diseases

Immune disorder
Classification and external resources
ICD-10	D80-D89
ICD-9-CM	273, 279
MeSH	D007154
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An immune disorder is a dysfunction of the immune system. These disorders can be characterized in several different ways:

According to the International Union of Immunological Societies, more than 150 primary immunodeficiency diseases (PIDs) have been characterized. However, the number of acquired immunodeficiencies exceeds the number of PIDs.

It has been suggested that most people have at least one primary immunodeficiency. Due to redundancies in the immune system, though, many of these are never detected.

Primary immune deficiency diseases are those caused by inherited genetic mutations. Secondary or acquired immune deficiencies are caused by something outside the body such as a virus or immune suppressing drugs.

Primary immune diseases are at risk to an increased susceptibility to, and often recurrent ear infections, pneumonia, bronchitis, sinusitis or skin infections. Immunodeficient patients may less frequently develop abscesses of their internal organs, autoimmune or rheumatologic and gastrointestinal problems.

An allergy is an abnormal immune reaction to a harmless antigen.

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