DNA polymorphism of the human complement C8 beta gene: formal genetics and intragenic localization.

The eighth component of human complement consists of three subunits of different molecular mass, which are coded for by three separate genetic loci. Polymorphisms have been described at the protein level for the alpha and beta subunits by means of sodium dodecyl sulfate gel electrophoresis and isoelectric focusing. Using a full-length human C8 beta cDNA probe, we have studied more than 100 individuals by Southern blot analysis to detect DNA polymorphisms. We have found two restriction fragment length polymorphisms (RFLPs) with the enzymes Taq I and Bam HI. The Taq I polymorphism is defined by two alleles, i.e., a single 4.9 kb fragment or two 2.8/2.1 kb fragments. The allele frequencies are…