DefinitionSelective deficiency of IgA is the most common immune deficiency disorder. Persons with this disorder have low or absent levels of a blood protein called immunoglobulin A.Alternative NamesIgA deficiencyCauses, incidence, and risk factorsIgA deficiency is usually inherited, which means it is passed down through families. However, cases of drug-induced IgA deficiency have been reported.It may be inherited as an autosomal dominant or autosomal recessivetrait. It is found in approximately 1 in 700 individuals of European origin. It is less common in people of other ethnicities.See also: Celiac disease - sprueSymptomsMost people with selective IgA deficiency have no symptoms.Symptoms include frequent episodes of:BronchitisChronic diarrheaConjunctivitis(eye infection)Mouth infectionOti