Selective C7 complement deficiency causing recurrent meningococcal infection.

We report on two sisters both with complete absence of the 7th component of complement. This congenital immunodeficiency disorder is associated with recurrent bacterial infection, especially that due to Neisseria species. These cases illustrate many of the well-recognised features of this disorder, but in one patient the illness was complicated by infective endocarditis due to N. meningitidis, a feature not previously reported.