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People with this condition lack immunoglobulin A (IgA), an antibody that protects the mucous membranes, or moist linings, of the eyes, mouth, airways, and digestive tract.
Selective IgA deficiency is caused by an inherited genetic defect in B cells that does not allow the cells to mature into normal IgA-producing cells.
People with IgA deficiency are more likely than the general population to be related to someone with common variable immunodeficiency (CVID).
Read about the gene linked to selective IgA deficiency.
The majority of people with selective IgA deficiency are healthy, with no more than the usual number of infections. Those who do have symptoms typically have recurring ear, sinus, or lung infections. People with selective IgA deficiency are likely also to have allergies, asthma, chronic diarrhea, and autoimmune diseases.
People with selective IgA deficiency have low levels of IgA antibodies in their blood, but they have normal levels of IgM, IgG, and complement (proteins that help antibodies fight bacteria) as well as normal numbers of T cells and phagocytes.
A doctor can diagnose selective IgA deficiency by measuring the total amount of IgA in the blood.
There is no specific treatment for selective IgA deficiency. In general, people are treated for infections, allergies, and autoimmune diseases if they occur.
Last Updated July 17, 2012
Last Reviewed October 15, 2010