IgAD1 is a condition in which people have very low or absent levels of immunoglobulin A (IgA) in the blood, while levels of immunoglobulin G and immunoglobulin M remain normal after the age of 4. Immunoglobulins are proteins that play an important role in fighting infections, and IgA is especially important in protecting mucosal surfaces such as those in the respiratory and digestive tracts. People with IgAD1 may not show any symptoms at all, or they may experience frequent infections, allergic reactions, or autoimmune disorders. The condition is diagnosed after excluding other causes of low immunoglobulins, making it important to carefully evaluate each case.

Some people with IgAD1 have no symptoms, while others may experience frequent infections, allergic reactions, or signs of autoimmune disorders. These symptoms arise because the body has a reduced ability to fight off infections at mucosal surfaces.

IgAD1 is linked to decreased or absent levels of IgA and is connected to the IGAD1 gene. It may be passed down in families through either autosomal recessive or autosomal dominant patterns, although the exact cause in some people may not be fully clear.