Immunoglobulin A Deficiency



Serum IgA <7 mg/dL and a normal serum IgG and IgM in patients >4 years of age

Risk Factors


  • Exact pattern of inheritance remains unclear; however, the following associations may occur:
    • 22q11 deletion syndrome
    • 18q syndrome
    • Partial deletions in the long or short arm and ring forms of chromosome 18
    • Also associated with HLA-A1, HLA-A2, B8, DR3, DQ2 (8.1), and Dw3
    • Also associated with non–MHC-associated genes involved in autoimmunity including IFIH1 on chromosome 2q24, CLEC16A on chromosome 16


  • Failure of B lymphocyte differentiation into plasma cells producing IgA
  • Block may be due to
    • Defect in T-helper cells
    • Antigen-presenting cells
    • B cells
    • Lack of effects from various cytokines, including IL-21, IL-4, IL-6, IL-7, or IL-10

Commonly Associated Conditions

Increased association with the following:

  • Atopy
  • Sinopulmonary infections
  • GI infections (especially Giardia lamblia)
  • Inflammatory bowel disease (Crohn disease and ulcerative colitis)
  • Celiac disease
  • Nodular lymphoid hyperplasia
  • Malignancy
  • Autoimmune illnesses
    • Systemic lupus erythematosus
    • Immune endocrinopathies (e.g., Graves disease, type 1 diabetes)
    • Autoimmune hematologic conditions
    • Chronic active hepatitis

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