IgAD1 (MONDO_0007644) is decreased or absent levels of serum immunoglobulin A, with normal serum levels of immunoglobulin G and immunoglobulin M in a patient who is older than 4 years of age and in whom all other causes of hypogammaglobulinemia have been excluded. Affected individuals may be asymptomatic or have frequent infections, allergic reactions, or autoimmune disorders. Also known as: IGAD1, immunoglobulin A deficiency, autosomal recessive, autosomal dominant, isolated cases.