Complement deficiencies
Complement is a series of proteins that circulate in plasma and are involved in the inflammatory and immune reaction of the body. Complement proteins are involved in chemotaxis, cell lysis and opsonisation
C1 inhibitor (C1-INH) protein deficiency
C1q, C1rs, C2, C4 deficiency (classical pathway components)
C3 deficiency
C5 deficiency
C5-9 deficiency
C1 inhibitor (C1-INH) protein deficiency
- causes hereditary angioedema
- C1-INH is a multifunctional serine protease inhibitor
- probable mechanism is uncontrolled release of bradykinin resulting in oedema of tissues
C1q, C1rs, C2, C4 deficiency (classical pathway components)
- predisposes to immune complex disease
- e.g. SLE, Henoch-Schonlein Purpura
C3 deficiency
- causes recurrent bacterial infections
C5 deficiency
- predisposes to Leiner disease
- recurrent diarrhoea, wasting and seborrhoeic dermatitis
C5-9 deficiency
- encodes the membrane attack complex (MAC)
- particularly prone to Neisseria meningitidis infection