[Purpura fulminans associated with a C7 deficiency]

A patient suffering from purpura fulminans was found to have a hereditary deficiency of the C7 component of complement. The homozygous deficiency of late acting complement components increases the risk of neisserial infection. CH50 titration will detect those patients suffering from a homozygous deficiency, who should be vaccinated against Neisseria meningitidis types.