Hereditary C5 deficiency and recurrent Neisseria meningitidis meningitis

Deficiencies of the terminal C fragments of the complement system are known to be associated with a remarkable increase in the frequency of Neisseria infections. The correlation is even closer between deficiency of C5 and recurrent N. meningitidis meningitis. The reasons for this bacterial specificity and the immunopathological mechanisms involved have not been clearly established. However, it is known that only adult subjects with homozygous deficiency are affected and that the deficiency is transmitted as an autosomal recessive trait unrelated to the HLA system.