TABLE 1.
Antibody deficiency disorders
| Disease | Laboratory feature(s) | Clinical feature(s) | Molecular defect(s) |
|---|---|---|---|
| Agammaglobulinemia (X linked and autosomal recessive) | Absent IgM, IgG, and IgA; B cells <2% of lymphocytes; absent specific antibody responses | Recurrent and severe bacterial infections, enteroviral infections, absent lymphoid tissue, some autoimmunity and malignancy | X linked (BTK), autosomal recessive (μ heavy chain, λ5, Igα, Igβ, BLNK, LRRC8), unknown in 5-10% of cases |
| CSR defects or hyper-IgM syndromes | Low IgG and IgA levels and normal-to-increased IgM levels, normal B-cell numbers, impaired specific antibody responses, decreased T-cell responses in CD40L/CD40 deficiency | Recurrent and severe bacterial infections, opportunistic infections and liver disease in CD40L/CD40 deficiency, lymphoid hyperplasia in AID/UNG deficiency, autoimmunity and malignancy | Intrinsic B-cell defects (AID, UNG), combined immunodeficiencies (CD40L, CD40) |
| CVID | Low IgG and variably low IgA and IgM levels, normal or decreased B-cell numbers, impaired specific antibody responses, variably decreased T-cell responses | Recurrent and severe bacterial infections, autoimmunity and malignancy, lymphoproliferative and granulomatous disease, gastrointestinal disorders | TACI, ICOS, CD19; unknown in 90% of cases |
| Selective IgA deficiency | IgA levels of <7 mg/dl and normal IgM and IgG levels, normal B-cell numbers, normal specific antibody responses in most patients | Usually asymptomatic; some association with atopy, autoimmunity, and gastrointestinal disorders | Unknown |
| IgG subclass deficiency | Low levels of one or more IgG subclasses; normal total IgG, IgM, and IgA levels; normal B-cell numbers; impaired specific antibody responses in some patients | Usually asymptomatic, some association with atopy and autoimmunity | Unknown |
| Specific antibody deficiency | Normal IgG, IgM, and IgA levels; impaired specific antibody responses (polysaccharides); normal B-cell numbers | Recurrent, predominantly respiratory tract bacterial infections | Unknown |
| THI | Low IgG levels and variably low IgA and rarely low IgM levels, normal specific antibody responses in most patients, normal B-cell numbers | Recurrent, predominantly respiratory tract bacterial infections | Unknown |