Virtual absence of serum and secretory IgA, and occasionally of IgG2 and IgG4 is relatively common, affecting 1 in 600 people. It may be familial or may be acquired following toxoplasmosis, measles, or other viral infections.
The basic defect is a failure of maturation of IgA positive B cells. Immature forms are present in normal numbers.
Last reviewed 01/2018