(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.

[4] Suspect terminal complement pathway deficiency in patients with more than one Neisseria infection episode.

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.

Patients with terminal complement pathway deficiency should receive meningococcal and pneumococcal vaccinations.