NCIt definition : 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.;