COMBINED GENETIC DEFICIENCY OF C6 AND C7 IN MAN

Abstract

By routine screening of sera, a subject was discovered who showed a subtotal deficiency of C6 and C7. No clinical disease was associated with this deficiency which was transmitted as a single genetic characteristic. The C6 deficiency was associated with a silent allele at the structural locus. The propositus had low quantities of an abnormal C6 which was antigenically deficient and smaller than normal C6 (110,000 daltons vs. 140,000 daltons) and small quantities of apparently normal C7. The subject may have a structural mutation in his C6 gene which produces hyopsynthesis of C6 and of closely linked C7. C6 and C7 may function as a single genetic unit. The primary transcript copied from the genome may include information for both proteins.