Immune deficiencies may be inherited, or have some other cause. If an immune deficiency is inherited, it is called a primary immune deficiency. Some examples of primary immune deficiencies are congenital hypogammaglobulinemia and severe combined immunodeficiency disease.
An immune deficiency can be caused by an infection, another disease, aging, poor nutrition, or a medication. This is called an acquired or secondary immune deficiency. Some examples of secondary immune deficiencies are acquired hypogammablobulinemia and AIDS.