The human serum transferrin (Tf) system was analyzed by isoelectric focusing (IEF) with immobilized pH gradients. For the demonstration of the genetic variability the Fe1-Tf region was chosen. The pH range suitable for analysis of the Tf system was pH 5.20 to pH 5.75. The phenotypes of the common six TfC subtypes are described. No further heterogeneity among TfC1, TfC2, and TfC3 was noted. Aslo presented are the phenotypes of the TfC6 subtype, and of three different TfB and three different TfD variants. IEF with immobilized pH gradients appears to be a suitable method for the analysis of the inherited transferrin polymorphism.

Gc subtypes were determined by immunofixation isoelectric focusing. In a family study involving 93 families with a total of 176 children, a three-allele model with six genotypes was confirmed. The distribution of Gc subtypes was studied in three populations from Europe and in a sample of Druzes from Northern Israel. Three new variant Gc types were observed.

The vitamin D3 binding properties of the common and rare Gc variants were examined. Vitamin D3 labeled with 14C was added to serum. Gc phenotypes were demonstrated autoradiographically following separation by immunofixation electrophoresis on agarose. This qualitative analysis did not reveal differences in vitamin D3 binding by the group-specific components of the common types Gc 1-1, Gc 2-1, and Gc 2-2. The double-band variants Gc Darmstadt, Gc Y/Ab, Gc Toulouse, Gc Norway, and Gc Caucasian were examined; the phenotypes Gc Ab-Ab, Gc Ab-1, Gc Ab-1, Gc Ab-2, Gc T-1, Gc T-2, Gc Norw-2, and Gc 1-Cau showed normal D3 binding. The double bands of Gc Darmstadt in the phenotype D-2 appeared somewhat weak. The single-band mutants Gc Wien, Gc Chippewa, Gc Opava, and Gc Z were analyzed; the phenotypes Gc W-1, Gc W-2, Gc Chip-1, Gc Chip-2, Gc 1-Op, Gc Op-2, Gc 1-Z, and Gc 2-Z showed normal D3 binding. A mutant in the Gc system with clearly defective vitamin D3 binding properties remains to be delineated.

Common and rare Gc phenotypes were analyzed by agarose gel electrophoresis immunofixation and by isoelectric focusing immunofixation before and after neuraminidase treatment. There is a difference between Gc types with double-band and with single-band patterns. Neuraminidase affects only Gc types with a double-band pattern: The double-band pattern is reduced to a single-band pattern. The anodal band disappears after removal of sialic acid by enzymatic cleavage; the cathodal band remains unchanged in its position and becomes stronger. Single-band Gc phenotypes remain unaltered after neuraminidase treatment.

Subtypes of the protease inhibitor (Pi) alpha 1-antitrypsin were determined in sera from 752 unrelated individuals from Southern Germany. By isoelectric focusing nine common PiM subtypes were distinguished and several rare Pi variants were observed. Family studies confirm the existence of a fourth PiM suballele. The frequency of PiM4 was found to be 0.018. A survey of the distribution of Pi alleles is given; the application of Pi subtyping in cases of disputed paternity is discussed.