TABLE 1.

Gene mutations in key PIDDs

Disorder	Inheritance	Gene mutations
Severe reduction in all immunoglobulin isotypes and absent B cells:
X-linked agammaglobulinemia	XL	Btk
Autosomal recessive agammaglobulinemia	AR	μ chain Igα Igβ λ5 BLNK
Severe reduction in at least 2 isotypes with normal or low B cell numbers:
Common variable immunodeficiency	AR	ICOS CD19 BAFFR SBDS
	AD or AR	TACI
Severe reduction in IgG and IgA with normal or increased IgM and normal B cell numbers:
CD40 ligand deficiency	XL	CD40XL
CD40 deficiency	AR	CD40
AID deficiency	AR	AICDA
UNG deficiency	AR	UNG
Individual isotype or light-chain deficiencies with normal B cell numbers:
Immunoglobulin heavy-chain deletions	AR	14q32 deletions
K chain deficiency	AR	K constant gene
Selective IgA deficiency	AD or AR	TACI

XL = X-linked; Btk = Bruton tyrosine kinase; AR = autosomal recessive; BLNK = B cell linker protein; ICOS = inducible co-stimulator; BAFFR = B cell activation factor of the TNF family receptor; SBDS = Shwachman-Bodian-Diamond syndrome gene; AD = autosomal dominant; TACI = transmembrane activator and calcium-modulating ligand interactor; AICDA = activation-induced cytidine deaminase; UNG = uracil-DNA glycolase.

Source: Adapted from Herriot 2008.