A faster migrating Gc-variant: Gc Darmstadt

Summary In three members of a family from Darmstadt (Germany) a faster migrating Gc variant has been observed. The variant phenotypes have been examined by routine immunoelectrophoresis (Fig. 1), by immunoelectrophoresis with prolonged separation times and with Gc-monospecific antisera (Fig. 2), by polyacrylamide gel electrophoresis (Fig. 3), and by antigen-antibody crossed electrophoresis (Fig. 4). By antigen-antibody crossed electrophoresis the new Gc variant was clearly distinguishable from the Gc Aborigine and from the Gc Chippewa variant. The variant was named Gc Darmstadt (Gc D). Gc Darmstadt has an electrophoretic migration rate intermediate between Gc Ab and Gc 1. In two sibs the type Gc D-2 was observed, the daughter of one of these sibs had the type Gc D-1. The analysis of several members of this family provided only limited information on the mode of inheritance of Gc Darmstadt (Fig. 5). Gc Darmstadt appears to be determined by a gene Gc^D which may be allelic to Gc¹ and Gc².

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Zusammenfassung Bei drei Angehörigen einer Familie aus Darmstadt (Deutschland) wurde eine schneller wandernde Gc-Variante beobachtet. Die neue Variante, die eindeutig von Gc Aborigine und Gc Chippewa unterschieden werden kann, wurde Gc Darmstadt (Gc D) genannt. Bei elektrophoretischer Auftrennung liegt Gc Darmstadt zwischen Gc Ab und Gc 1. Gc Darmstadt ist sehr wahrscheinluch durch ein Gen Gc^D bedingt, das ein Allel zu Gc¹ und Gc² ist.

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Supported by U.S.-PHS Grant AM 11796 and aided by a grant from the Deutsche Forschungsgemeinschaft, Bad Godesberg.     

A new hereditary single band variant of the Gc system

Summary A new single band variant (Gc Ar) or the Gc subtypes not identical with the known Gc variants has been detected in the plasma of a healthy blood donor by isoelectric focusing. Using this technique the variant is represented by a single band which has a similar isoelectric point to the Gc 1C2 anodal band. It is well known that the single band Gc phenotypes remain unaltered after neuraminidase treatment. Nevertheless, the new single band variant (Gc Ar) is altered after neuraminidase treatment as is Gc 2A3. After neuraminidase treatment, the Gc Ar band is affected and moved to the nearby position of the Gc 2 band. Investigation of the proband's family shows that the variant occurs combined with the common alleles Gc 1F, Gc 1S and that it has an autosomal dominant inheritance.     

Gc revisited: Six further Gc-phenotypes delineated by isoelectric focusing and by polyacrylamide gel electrophoresis

Summary Six newly observed Gc variants are described. The variants Gc 1A10, 1A11, 1A12, 1A13, and 1C11 have double band patterns. The anodal bands of these variants are susceptible to neuraminidase treatment. Gc 2A7 is a single band variant which is not altered by neuraminidase incubation. Polyacrylamide gel isoelectrofocusing with immunofixation and polyarcylamide gel electrophoresis appear to be efficient methods for the analysis of the Gc system.     

Population genetic studies of the Philippine Negritos. I. A pilot survey of red cell enzyme and serum protein groups

Electrophoretic surveys of red cell enzyme and serum protein systems representing 21 genetic loci were carried out on 129 blood samples of the Negritos of Pampanga, Central Luzon, the Philippines. Nine (out of 16) red cell enzyme loci and four (out of five) serum protein loci showed polymorphic variation. Low frequencies of ACP 1A, GPTs1, ESD2, and Hp1, and a markedly high frequency of PGM12 were contrasted to those in non-Negrito Filipinos. Variant ESD phenotypes with a slowly migrating isozyme occurred in high frequency. The new allele designated as ESD3Negrito (ESD3N) had a frequency of .10 +/- .019. In AK, a variant phenotype indistinguishable from AK 2-1 was observed in 14% of the sample. In the Gc system, a fast migrating variant was discovered in high frequency which was distinct from Gc Ab and Gc J. The variant allele, denoted GcNegrito (GcN), had a frequency of .21 +/- .025. A relatively high degree of allelic diversity in the Negrito sample was also suggested by the average heterozygosity for 21 loci screened (.165), which is compared to that of the Japanese population (.140).     

Hereditary recombined three-allele variant of the Gc system

A three-allele variant with Gc 2, Gc 1F and Gc 1A2 alleles was detected in both a baby and his mother during paternity testing by isoelectric focusing. His father had a normal Gc phenotype, Gc 2-1F. Further examination of his mother's relatives revealed that his grandfather also had the same three-allele variant, while his grandmother and his aunt had normal Gc 2-1F and Gc 2-2. From these results, it was considered that the Gc 1F and Gc 1A2 alleles were on the same single chromosome. It was suggested that recombination had occurred between two chromosomes that had the Gc 1F and Gc 1A2 allele, respectively, forming the variant allele Gc 1F1A2 on a single chromosome.     

Five new Gc variants detected by isoelectric focusing in agarose gel

Summary Five new genetically determined Gc variants were observed by isoelectric focusing. Seven rare variants 1A4, 1C1, 1C3, 1C9, 1C11, 2A2, and 2A5 were also found in the material comprising Danish ans Swedish paternity cases. All the variants were further analysed by electrophoresis in agarose gel. Two of the new variants had double bands of which the anodal one was susceptible to neuraminidase treatment (Gc 1C13 and 1C14). The three other new variants appeared as a single band, which was unaffected by neuraminidase treatment (Gc 2A9, 2C5, and 2C6). The Gc Ar variant originally detected by electrophoresis was reexamined by isoelectric focusing and named 2C4.     

Post-translational heterogeneity of the human vitamin D-binding protein (group-specific component)

The vitamin D-binding protein in human serum (the group-specific component) is an alpha 2-globulin which is genetically polymorphic in all populations studied. Previous work (J. Svasti and B. H. Bowman (1978) J. Biol. Chem. 253, 5188-5194, and J. Svasti, A. Kurosky, A. Bennett, and B. H. Bowman (1979) Biochemistry 18, 1611-1617) has shown that the electrophoretic variations of the proteins controlled by two allelic genes, Gc1 and Gc2, are due to at least three amino acid substitutions between Gc1 and Gc2 (Svasti et al. (1979] and to heterogeneity in the Gc1 phenotype arising from carbohydrate dissimilarities. Gc1 migrates electrophoretically as two protein bands, while Gc2 migrates cathodally as a single band. This study demonstrates a post-translational glycosylation difference occurring in a single area of the Gc1 sequence which accounts for the heterogeneity observed previously. The glycosylation site, a threonine residue, appears to be in a sequence which differs between Gc1 and Gc2. The O-glycosidic bond, which is typical of mucins, is rare in plasma proteins. The cyanogen bromide fragment containing the galactosamine-containing carbohydrate in Gc1 was partially sequenced through 20 residues from the amino terminus. No detectable galactosamine could be found in the homologous cyanogen bromide fragment in Gc2. A new purification procedure for the vitamin D-binding protein in human plasma has been developed. Three chromatographic steps provide purified protein.     

Unusual sialilation of three different rare genetic variants of serum DBP: Gc 1A17, Gc 1A16, and Gc 1A11

Summary The proteins of three anodal Gc1 variants, Gc 1A16, 1A11, and 1A17, are characterized by the most acidic isoelectric points observed so far among the different Gc mutants. Stepwise removal of N-acetylneuraminic acid (NANA) by treatment with neuraminidase was performed to estimate the degree of sialilation of these Gc variants. The results indicate that both proteins, the anodal and the cathodal component of these Gc 1 mutants, carry sialic acid residues. This observation is remarkable in so far as usually only the anodal component of the Gc 1 protein contains NANA and only a single residue. From the experiments carried out it can be deduced that Gc 1A16 has two NANA residues in the anodal and one NANA residue in the cathodal component. Gc 1A16 was found in four members of three generations in a Danish family; the variant segregated as a Mendelian trait. More difficult to interprete are the results obtained with the variants Gc 1A11 and Gc 1A17. Gc 1A11 probably has three NANA residues in the anodal and two NANA residues in the cathodal component. Gc 1A11 has been observed in two mother-child pairs and is presumably also a simple genetic trait. Gc 1A17 has also several NANA residues in both Gc proteins; it is suggested that the anodal component has either three or four NANA residues and the cathodal component either two or three NANA residues. Family information on this variant is not yet available.     

Gc X and Gc Y revealed by immunofixation electrophoresis

Summary Immunofixation electrophoresis is used to define two variants in the Gc system: Gc X and Gc Y. Gc X has one band with a mobility between Gc 1-1 and Gc 2-2 while Gc Y has two bands migrating faster than the cathodal band of Gc 1.     

The vitamin D binding of the common and rare variants of the group-specific component (Gc)

Summary 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 Gc1-1, Gc 2-1, and Gc2-2. 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-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 singleband 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.     

Phenotype frequencies of vitamin D binding protein (Gc) and of posttransferrin-2 (Ptf-2) in Belgian cattle breeds*

The vitamin D binding protein (Gc) and posttransferrin-2 (Ptf-2) phenotypes have been determined in a number of Belgian cattle breeds. A very slow migrating variant of the Gc protein — Gc C — has been found in White and Red East Flemish breed. This variant was absent from the other breeds studied. This slow variant was identified as a vitamin D binding protein by autoradiography. The Gc C protein was shown to be controlled by a codominant autosomal allele Gc C at the Gclocus. The Gc C protein is probably identical with a fraction previously described in buffalo and an Italian cattle breed. The allele frequencies for the Gc and Pft-2 systems are reported for several Belgian breeds of cattle.     

Frequency of Gc alleles and a variant Gc allele in Iceland

The gene frequency for Gc1 and Gc2 in an Icelandic population was found to be 0.71 and 0.29, respectively. An electrophoretic variant similar to Gc Norway was detected in 5 individuals of the same family. A pedigree of 14 family members, including two spouses, is presented.     

Genetic polymorphism of group-specific component/vitamin-D-binding protein subtypes in six populations from north-eastern China

On six populations from North-Eastern China the frequencies of Gc subtypes were studied by isoelectric focusing on ultra-thin polyacrylamidegel followed by the improved sulfosalicylic acid precipitation. The following Gc subtype allele frequencies could be observed in the Han (Harbin), Ewenki, Tahur, Mongolian, Oroquen and Xibe populations: Gc*1F = 0.4246, 0.4941, 0.4479, 0.4077, 0.4606 and 0.4503; Gc*1S = 0.2587, 0.2936, 0.3151, 0.2822, 0.3370 and 0.3035; Gc*2 = 0.3065, 0.2064, 0.2266, 0.3006, 0.2022 and 0.2388. In addition to this 16 individuals of five populations showed rare Gc variant alleles (1A3, 1A8, 1A9, 1A14, 1C?).     

Polymorphic plasma postalbumin (Po) of llamas and alpacas identified as Gc protein

Immunoblotting with antiserum specific to human Gc protein was used to identify Gc protein as the previously reported polymorphic plasma postalbumin (Po) of llamas and alpacas. This is the first report of Gc polymorphism in camelid species. One Gc variant appeared to be identical in llamas, alpacas, dromedaries and bactrian camels.     

Group-specific component, alpha1-antitrypsin and esterase D in Canadian Eskimos.

Three genetic markers - group-specific component (Gc), alpha1-antitrypsin, and esterase D - were examined in a population of Eskimos from Igloolik in the eastern Canadian Arctic. Gc and esterase D were found to be polymorphic. In addition to the common Gc types, an anodal variant called Gc Igloolik was found, probably identical to previously reported Gc Eskimo. Gene frequencies were Gc1: 0.6524, Gc2: 0.3373, GcIgl: 0.0104, for 338 Eskimos. Genetic types of alpha1-antitrypsin (Pi types) were mostly M, with two MS sibs who were half Caucasian, in 170 Eskimos. Frequencies of the esterase D allele in 336 Eskimos were EsD1: 0.7083, EsD2: 0.2917. The frequencies of Gc2 and EsD2 are both higher than are found in Caucasian populations.     

Polymorphic plasma postalbumin (Po) of llamas and alpacas identified as Gc protein

Summary. Immunoblotting with antiserum specific to human Gc protein was used to identify Gc protein as the previously reported polymorphic plasma postalbumin (Po) of llamas and alpacas. This is the first report of Gc polymorphism in camelid species. One Gc variant appeared to be identical in llamas, alpacas, dromedaries and bactrian camels.     

Gc subtypes in Northern Indians

Isoelectric focusing was used to determine the frequencies of the Gc subtypes in a population sample from The North Indian subcontinent (now living in Birmingham, UK). The gene frequencies observed were as follows: Gc1F = 0.191, Gc1S = 0.519 and Gc2 = 0.290.243 individuals were typed and no variant alleles were detected.     

Gc types in western Japan: report of a new variant Gc 1C35

Gc types were examined in a total of 1,000 unrelated Japanese individuals from Western Japan. By isoelectric focusing the six common subtypes and several rare types were observed. In addition, a new variant with a mobility between the Gc 1S and 1C2 was identified in 2 individuals. A family investigation confirmed the inheritance of the corresponding allele Gc* 1C35.     

白、苗、土家、彝族组特异性成分亚型的研究

用薄层聚丙烯酰胺凝胶等电聚焦结合免疫固定的方法分析了中国四个少数民族的组特异性成分(Gc)的亚型分布。白族、苗族、土家族、彝族Gc~1F的基因频率分别为0.4082,0.4229,0.3592,0.4248;Gc~1S的基因频率分别为0.3035,0.2687,0.2864,0.3301,Gc~2的基因频率分别为 0.2577,0.3035,0.3342,0.2208。另外,在四个民族中发现十六个个体带有Gc的罕见变异型等位基因。     

Genetic polymorphism of the vitamin D binding protein (Gc) in the musk shrew (Suncus murinus)

In the musk shrew ( Suncus murinus ), the electrophoretic bands in the post-albumin region were identified as vitamin D binding protein (Gc) by the [³HI vitamin D₃ binding method. Three Gc phenotypes were distinguished from each other: a single faster band (Gc-A), a single slower band (Gc-B) and the double bands (Gc-AB). Results of mating experiments indicated that the Gc-A and Gc-B are controlled by two codominant alleles, Cc ^a and Gc ^b at an autosomal locus ( Cc ), respectively. It was noticed that, in the Gc-AB phenotypes, the Gc-B band was constantly more intense than the Gc-A band in the protein staining. The same tendency was also observed btween the homozygous Gc-A and Gc-B bands, and further, radioactivity of the Gc-B bound with [³H] vitamin D₃ was about twofold higher than that of the Gc-A. These results suggest that the Gc^b yields its protein product twofold more than the Gc ^a. No cross-reaction between the shrew proteins and a rabbit anti-human Gc protein was observed.