Terminal complement pathway deficiency

Terminal complement pathway deficiency
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]

Diagnosis

Complement tests

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

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.

References

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.