Immunoglobulin deficiency syndromes are a group of immunodeficiency disorders in which the patient has reduced number of or lack of antibodies.

Immunoglobulins (Ig) are antibodies. There are five major classes of antibodies: IgG, IgM, IgA, IgD, and IgE.

• IgG is the most abundant of the classes of immunoglobulins. It is the antibody for viruses, bacteria, and antitoxins. It is found in most tissues and plasma.
• IgM is the first antibody present in an immune response.
• IgA is an early antibody for bacteria and viruses. It is found in saliva, tears, and all other mucous secretions.
• IgD's activity is unknown.
• IgE is present in the respiratory secretions. It is an antibody for parasitic diseases, hay fever, and allergic asthma.

All antibodies are made by B-cells. Any disease that harms the development or function of these cells will cause a decrease in the amount of antibodies...