Terminal complement pathway deficiency

A rare immunodeficiency disorder affecting the complement system

Terminal complement pathway deficiency is a rare immunodeficiency disorder that affects the complement system, specifically the terminal components of the complement cascade. This condition results in an increased susceptibility to certain types of bacterial infections, particularly those caused by Neisseria meningitidis.

Overview

The complement system is a crucial part of the innate immune system, consisting of a series of proteins that work together to fight infections, clear pathogens, and promote inflammation. The terminal complement pathway involves the formation of the membrane attack complex (MAC), which is essential for lysing and killing certain bacteria.

Pathophysiology

In terminal complement pathway deficiency, there is a defect in one or more of the components of the terminal complement pathway, typically C5, C6, C7, C8, or C9. This defect impairs the formation of the MAC, reducing the body's ability to lyse and kill certain bacteria, particularly Neisseria species.

Clinical Manifestations

Individuals with terminal complement pathway deficiency are particularly susceptible to recurrent infections with Neisseria meningitidis, which can lead to meningitis and septicemia. These infections can be severe and life-threatening if not promptly treated.

Diagnosis

Diagnosis of terminal complement pathway deficiency is typically made through laboratory tests that measure the activity of the complement system. These tests can identify deficiencies in specific complement components. Genetic testing may also be used to identify mutations in the genes encoding these proteins.

Management

Management of terminal complement pathway deficiency involves preventive measures to reduce the risk of infection. This includes vaccination against Neisseria meningitidis and prophylactic antibiotics. Patients are also educated about the signs and symptoms of meningococcal infections and the importance of seeking immediate medical attention if they occur.

Prognosis

With appropriate preventive measures and prompt treatment of infections, individuals with terminal complement pathway deficiency can lead relatively normal lives. However, they remain at increased risk for severe infections and must be vigilant about their health.

Related pages

• Complement system
• Immunodeficiency
• Neisseria meningitidis
• Membrane attack complex