TABLE 3.

Classification of Immune System Component Defects

Type of component defect	Description	% of PIDD disorders	Common associated disorders
B-cell defects	Antibody production deficiencies Decreased antibody titers B-cell dysfunction	50–60%	Selective IgA deficiency XLA CVID IgG subclass deficiency Specific antibody deficiency Autosomal recessive agammaglobulinemia Selective IgM deficiency Good’s syndrome
T-cell defects	Immunoglobulin deficiencies	5–10%	DiGeorge syndrome ZAP-70 deficiency X-linked lymphoproliferative syndrome Chronic mucocutaneous candidiasis
Combined B- and T-cell defects	Impaired antibody formation	20%	Severe combined immunodeficiency Ataxia-telangiectasia
Natural killer-cell defects	Probable predisposition to viral infection and tumors (very rare)	NA	NA
Phagocytic-cell defects	Impaired pathogen destruction	10–15%	Chronic granulomatous disease Leukocyte adhesion deficiency syndrome Chédiak-Higashi syndrome
Complement defects	Deficiencies of complement components or inhibitors	≤2%	Systemic lupus erythematosus (SLE) Pyogenic infections Autoimmune disorders Angioedema Paroxysmal nocturnal hemoglobinuria Leukocyte adhesion deficiency syndrome

CVID = common variable immunodeficiency; Ig = immunoglobulin; XLA = X-linked agammaglobulinemia; ZAP-70 = Z-associated protein 70.

Sources: Adapted from Bonilla 2005, Merck Manual 2010.