To the Editor.
—In the July Archives Zimran et al1 described a Sephardic Jewish family in which one out of three subjects with an inborn deficiency of the C8 component of serum complement had recurrent meningococcal meningitis. They mentioned that genetic defects of terminal complement components, more particularly of C6, C7, and C8, predispose to generalized and often recurrent neisserial infections. We wish to describe a white family (Figure) in which two sisters had undetectable complement hemolytic activity (CH50) titers; C5 was immunochemically undetectable and was 1% of the normal C5 level by hemolytic assay. One of the sisters developed meningitis with meningococcemia (group C) at the age of 20 years and Neisseria meningitidis (group B) meningitis three years later; the other one presented with a presumptive gonococcal arthritis-dermatitis syndrome at the age of 24 years. Both symptomatic sisters were homozygotes for C5 deficiency, whereas 20 other family members