Complement regulatory protein defects, including the following six diseases:
C1 inhibitor deficiency (hereditary angioedema);
C4 binding protein alpha deficiency;
C4 binding protein beta deficiency;
Factor I deficiency;
Decay-accelerating factor (CD55) deficiency;
CD59 deficiency

To prevent undesirable complement activation, host tissues express a number of complement regulatory proteins. They include C1 inhibitor (C1-INH, also termed SERPING1), C4 binding protein (C4BP), Factor I, decay accelerating factor (DAF), CD59, and so on. C1-INH (SERPING1) deficiency can be genetic or acquired, and this causes an episodic, local increase in vascular permeability in the subcutaneous and submucosal layers, identified as angioedema (hereditary or acquired). Genetic deficiency of C4BP has only been reported in one individual who developed an illness with similarities to Behcet's syndrome. Heterozygous mutations within the Factor I gene have been recently identified in individuals with atypical hemolytic uremic syndrome (aHUS), while homozygous deficiency of Factor I is an unusual feature. Factor I-deficient patients present high susceptibility to respiratory tract infections and meningitis. Kidney impairment and autoimmune disorders have also been observed. Only a single case of CD59 deficiency has been reported and this individual developed a paroxysmal nocturnal haemoglobinuria(PNH)-like illness. In contrast, deficiency of DAF is not associated with haemolytic anaemia.

Primary immunodeficiency

SERPING1 [HSA:710] [KO:K04001]
C4BPA [HSA:722] [KO:K04002]
C4BPB [HSA:725] [KO:K04003]
IF [HSA:3426] [KO:K01333]
DAF [HSA:1604] [KO:K04006]
CD59 [HSA:966] [KO:K04008]

PMID:19481265 (description, gene)

Botto M, Kirschfink M, Macor P, Pickering MC, Wurzner R, Tedesco F

Complement in human diseases: Lessons from complement deficiencies.

Mol Immunol 46:2774-83 (2009)

PMID:19162547 (description, gene)

Cugno M, Zanichelli A, Foieni F, Caccia S, Cicardi M

C1-inhibitor deficiency and angioedema: molecular mechanisms and clinical progress.

Trends Mol Med 15:69-78 (2009)

PMID:18374984 (description, gene)

Ponce-Castro IM, Gonzalez-Rubio C, Delgado-Cervino EM, Abarrategui-Garrido C, Fontan G, Sanchez-Corral P, Lopez-Trascasa M

Molecular characterization of Complement Factor I deficiency in two Spanish families.

Mol Immunol 45:2764-71 (2008)

PMID:17162365 (gene)

Kumar A, Teuber SS, Gershwin ME.

Current perspectives on primary immunodeficiency diseases.

Clin Dev Immunol 13:223-59 (2006)

PMID:17952897 (gene)

Geha RS, Notarangelo LD, Casanova JL, Chapel H, Conley ME, Fischer A, Hammarstrom L, Nonoyama S, Ochs HD, Puck JM, Roifman C, Seger R, Wedgwood J.

Primary immunodeficiency diseases: an update from the International Union of Immunological Societies Primary Immunodeficiency Diseases Classification Committee.

J Allergy Clin Immunol 120:776-94 (2007)