The complement factor 6 polymorphism has been examined in a Norwegian family material by two techniques: either high voltage agarose gel electrophoresis or isoelectric focusing in polyacrylamide gel slabs. Proteins with C6 activity were visualized by a specific, hemolytic assay. Agarose electrophoresis gave good separation of common allele products and easy discrimination between the common C6 types: C6A, C6AB, and C6B. Prolonged isoelectrofocusing gave better band separation, but the discrimination between the common C6 types is not noticeably better than with the agarose technique. For detection of rare alleles isoelectrofocusing is presumably the method of choice.
In a Norwegian population sample, C6 gene frequencies were: C6A: 0.61 and C6B: 0.39.
The data on the linkage relationship between the HLA region loci and C6 show that C6 complement locus is not within measurable distance to the HLA region. Linkage studies also indicate nonlinkage between C6 and another chromosome 6 marker locus, PGM3. C6 has therefore been excluded from a substantial portion of the short arm of chromosome 6.