IgA deficiency is an IgA level < 10 mg/dL with normal IgG and
IgM levels. It is the most common primary immunodeficiency. Many
patients are asymptomatic, but some develop recurrent infections
and autoimmune disorders. Some patients develop common variable
immunodeficiency, and some remit spontaneously. Diagnosis is by
measuring serum Igs. Treatment is avoidance of blood products
that contain IgA; antibiotics are given as needed. IgA
deficiency affects up to 1/333 people. Transmission is autosomal
dominant with incomplete penetrance. IgA deficiency is commonly
associated with certain HLA haplotypes, and rare alleles or
deletions of genes in the major histocompatibility complex (MHC)
class III region (see Biology of the Immune System: Human
Leukocyte Antigen (HLA) System) are common. IgA deficiency also
occurs in siblings of children with common variable
immunodeficiency (CVID) and evolves into CVID in some patients.
Use of drugs such as phenytoin, sulfasalazine, colloidal gold
and d-penicillamine may lead to I