Abstract. A new method of C 3 type determination on high voltage agarose gel electrophoresis is described. The influence of some electrophoretic variables on the results has been investigated and a standard technique developed. The method is quick, simple and gives good separation of C 3 proteins. The three common C 3 phenotypes and the four variant types so far studied are easily demonstrated. Preliminary allele frequencies in a Norwegian population sample is presented. The values found, C 3S = 0.80 and C 3F = 0.19, are in good accordance with the allele frequencies in two population groups of North American Caucasians.

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By two-dimensional electrophoresis of human serum a genetically determined polymorphism of apolipoprotein E (apoE) can be demonstrated. Three alleles occur with appreciable frequency in Caucasian populations. In the present study the segregation of apoE and complement component C3 (C3) types in material from Norwegian families has been studied. Linkage has convincingly been demonstrated between the two loci with a lod score of 3.00 in males at a recombination fraction of 13%. As it is known that the C3 locus is situated on chromosome 19 in man, apoE can be located to this specific chromosome. Positive linkage data do not, to our knowledge, at present exist with regard to other apolipoproteins.

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Isofocusing and immunoblotting of reduced serum samples identify the common haptoglobin α-chain variants 1S, 1F, 2FS, 2SS, 2FF, 3, as well as several rare α- and β-chain variants. The gene frequencies found in 6,668 unrelated persons involved in Norwegian paternity cases were: HP*1S: 0.22, HP*1F: 0.16, HP*2FS: 0.58, HP*2SS: 0.04, HP*2FF: 0.004, HP*3: 0.0004, other HP*α variants: 0.0004, HP*β variants: 0.0008. The corresponding gene frequencies in 153 unrelated Norwegian Saamis (Lapps) were: HP*1S: 0.19, HP*1F: 0.07, HP*2FS: 0.70, HP*2SS: 0.04. Norwegians and Norwegian Saamis differed both in phenotype and allele distribution. An earlier Norwegian population study has shown a lower HP*1 frequency in the north than in the south. This regional difference in haptoglobin gene distribution was reflected in the present material as a lower 1F frequency, indicating a Saamish influence in northern Norway. Furthermore, the relatively low 2FF frequency in the north coincides with the lack of observed 2FF genes in the Saamish population. Non-Scandinavians involved in Norwegian paternity cases did not differ from the rest of the material. A review of published haptoglobin gene frequencies shows the 1F frequency to be a good indicator of ethnic origin, and that 2FF and 2SS frequency determinations may also be valuable in genetic population studies.

C 3 type determinations were performed in 2,454 unrelated Norwegians. The following frequencies were found for the 2 common alleles at the C 3 locus: C 3^S= 0.7865 and C 3^F = 0.2082. Nine different variant phenotypes were found in 26 individuals. No heterogeneity in phenotype distribution between different regions of Norway was observed. It was shown that no association exists between C 3 phenotypes and sex. The allele frequencies of this material resemble those of other Caucasian population groups tested closely, but differ significantly from the allele frequencies of Negro, Oriental and Lappish populations tested.

Summary C4‐coated Ch(a+) red blood cells (RBC) were used as indicator cells in a serum inhibition reaction of anti‐Cha, for the determination of the Ch group of serum. This serological study, combined with electrophoretic studies of C4 in a family material, showed that the C4M haplotype product was associated with partial inhibition of anti‐Cha.

Further data on the Gb - HL-A linkage relationship are presented. All three GBG informative recombinants investigated are Gb - first HL-A recombinants; therefore Gb must be situated on the second HL-A side of the first HL-A locus. Ninety additional apparently Gb - HL-A non-recombinant offspring from 23 matings indicate that the Gb locus is situated in clsoe proximity to the second HL-A locus.