A silent gene (C3-) producing partial deficiency of the third component of human complement

A family is described with 3 members in 3 generations being heterozygous for the silent gene C3-: one girl, her mother and grandfather had half normal C3 levels and were apparently incompatible homozygous. No significant deviation in the total hemolytic complement activity, serum concentration of Bf and C4 component was found in the affected individuals.