N. meningitidis can be due to deficiency of this complement system:

C5 - C9 - MAC (membrane attack complex) deficiency can lead to increased risk of meningococcal disease. C1, C2, and C4 deficiencies are associated with pyogenic infections and rheumatologic disorders, paicularly systemic lupus erythematosus. C3 deficiency is also associated with pyogenic infections and rheumatologic disorders