Terminal complement pathway deficiency

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Terminal complement pathway deficiency
Complement death.PNG
complement membrane attack complex
Classification and external resources
OMIM 120950 609536, 612446, 610102

Terminal complement pathway deficiency is a genetic condition affecting the complement membrane attack complex (MAC).

It involves deficiencies of C5, C6, C7, and C8. (While C9 is part of the MAC, and deficiencies have been identified,[1] it is not required for cell lysis.[2])

People with this condition are prone to meningococcal infection.[3] Vaccination may be recommended.[4]


Complement tests
C4 (C) FB (A) C3 CH50 Conditions
 · PSG, C3 NeF AA
 ·  · HA, C4D
 ·  ·  · TCPD
 · /↓ SLE

Initial complement tests often include C3 and C4, but not C5 through C9. Instead, the CH50 result may play a role in diagnosis: if the CH50 level is low but C3 and C4 are normal, then analysis of the individual terminal components may be warranted.


  1. ^ Lint TF, Zeitz HJ, Gewurz H (November 1980). "Inherited deficiency of the ninth component of complement in man". J. Immunol. 125 (5): 2252–7. PMID 7430628. 
  2. ^ Thomas M. Habermann; Mayo Clinic (1 November 2007). Mayo Clinic Internal Medicine Concise Textbook. CRC Press. pp. 30–. ISBN 978-1-4200-6749-1. Retrieved 14 November 2010. 
  3. ^ J.K. Sinha & S. Bhattacharya. A Text Book of Immunology. Academic Publishers. pp. 385–. ISBN 978-81-89781-09-5. Retrieved 14 November 2010. 
  4. ^ Frederick S. Southwick (10 December 2007). Infectious diseases: a clinical short course. McGraw Hill Professional. pp. 149–. ISBN 978-0-07-147722-2. Retrieved 14 November 2010.