IgA deficiency

• Facts:
  MC primary immunodeficiency
  
  Genetic B-cell deficiencies present after 6 months, when newborn's levels of maternal antibodies drop
  
  Affected infants are predisposed to recurrent sinopulmonary infections with encapsulated organisms
  
  Also, since IgA inhabits GI tract, predisposed to Giardia infections
• Diagnosis:
  Low IgA
  IgG subclass 2 may also be low
• Associated With:
  Anaphylaxis after immunoglobulin exposure (blood transfusions)