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There are many types of PI, but they all affect the immune system.

Primary immunodeficiency (PI) is a term used to describe more than 400 disorders. Although they all have differences, what these disorders all have in common is that they cause the immune system to not work right, in some cases making it harder to fight off infections. PI is a chronic disorder that causes your immune system to work improperly. This leads to increased chance of an infection. And because the types of infections can vary, diagnosing PI can be difficult.

Types of primary immunodeficiency

Types of PI include selective IgA deficiency, common variable immune deficiency (CVID), X-linked agammaglobulinemia (XLA), and severe combined immune deficiency (SCID).

Primary immunodeficiency
can't be
caught or spread

Primary immunodeficiency is not contagious. It is usually inherited, which means it may run in families; however, some of the disorders may be caused by both genetic and environmental components.

What primary immunodeficiency is not

Primary immunodeficiency should not be confused with autoimmune disorders or secondary immunodeficiencies.

In an autoimmune disorder (like rheumatoid arthritis or Type 1 diabetes), the immune system gets confused and attacks the body.

With secondary immunodeficiency, something else causes the immune system to not work right, like another infection or a medical treatment (such as chemotherapy). The most common type of secondary immunodeficiency is AIDS, which is caused by the human immunodeficiency virus (HIV).

With primary immunodeficiency, a part of the immune system is either missing or not working correctly. Primary immunodeficiency diseases are mainly genetic defects that may be passed down in families.

How PI is diagnosed. And why it can be misdiagnosed.

Though they were once thought to be rare, primary immunodeficiencies, as a group, are now considered more common. As PI awareness among physicians continues to grow and better diagnostic tools are available, more people are getting diagnosed.

Primary immunodeficiency symptoms

Susceptibility to infections is one of the most common symptoms of PI. However, the symptoms can vary, and they can be mistaken for common infections, since even healthy people without PI can get sick frequently.

This is one of the reasons it can be difficult to diagnose PI. In fact, according to the 2013 Immune Disease Foundation survey, a PI diagnosis can take about 15 years on average from the time symptoms begin.

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on average



Once thought to be a child's disease, we now know that PI can be diagnosed at any age. When testing for PI, doctors will ask about your family history and do a physical exam. They will also order blood tests to check if your blood cells, antibodies, and immune system are working properly. These tests are important for your doctor to confirm a diagnosis of PI and to determine the type of PI you have.

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