What is primary immunodeficiency?

Primary immunodeficiency occurs when part of a person’s immune system is missing or does not work correctly.  The bodies of people with primary immunodeficiency can’t get rid of germs or protect themselves from new germs as well as they should.

Primary immunodeficiencies are inherited, meaning they are passed down from parents to children.

These immunodeficiencies range from very serious to very mild.  The serious forms are often noticeable at birth or shortly thereafter.  However, very mild forms may not be diagnosed until later in life, during adolescence or young adulthood.

The World Health Organization has identified more than 80 kinds of primary immunodeficiency diseases.  But, the general category includes more than 100 diseases caused by an immune system that doesn’t function properly.