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。     

Gc subtyping in south Indian tribal and caste populations

Seven tribal (Konda Kammara - 2 samples; Koya Dora - 3 samples; Lambadi) and caste (Madiga) populations from Andhra Pradesh (South India) have been analyzed for the distribution of Gc subtypes. The observed heterogeneity in the distribution of Gc1F, Gc1S and Gc2 alleles was found to be statistically significant. Comparisons are made with North Indian populations as well as with those of other racial affiliation. The anthropological impact of the Gc subtype polymorphism is discussed.     

Group-specific component (Gc): subtypes in the Finnish population. Description of a new allele and an apparent mother-child incompatibility

The group-specific component (Gc) subtypes were determined in 575 adult Finns by immunoblotting after isoelectric focusing in agarose gel. The gene frequencies were Gc1S = 0.661, Gc1F = 0.139 and Gc2 = 0.200. This material included one rare allele, a more acidically focusing Gc 2 (named Gc 2A18). The phenotypes of 200 mother-child pairs studied were in accordance with the three-allelic mode of inheritance. An apparent mother-child incompatibility observed during routine paternity testing is reported.     

On the variability of Gc subtypes in Italy

909 individuals from different places of Italy were analyzed for the distribution of Gc subtypes. The observed heterogeneity in the distribution of the allele frequencies was found to be statistically significant. Comparing our results with those reported by other authors it is seen that within Italy a considerable regional variation in the frequencies of the Gc subtype alleles is present. However, there are no indications for any particular distribution patterns or gradients. In one of our samples (Bari district), one case of Gc 1S-1C3 was found.     

Population distribution in North and Central America of PGM1 and Gc subtypes as determined by isoelectric focusing (IEF)

Gc subtypes of 20 North and Central American populations and PCM₁ subtypes in 11 populations were analyzed to identify interpopulation variation of the respective gene frequencies for common alleles. A total of 23,304 phenotypings were done. Absolute heterozygosity levels (D) generally increased twofold when phenotyping by isoelectric focusing was compared with conventional electrophoresis. Graphic representation of the Gc subtypes and multivariate analysis to identify genetic affinities of the populations under study reveal genetic clusters consistent with major historical and geographical groupings of man.     

Distribution of transferrin and group-specific component subtypes among Parsis of India

Transferrin and group-specific component subtypes were studied by isoelectric focusing of sera from 253 Parsis in India. The frequencies of TfC1, TfC2, TfC3 and TfC4 were found to be 0.8083, 0.1719, 0.019 and 0.0020, respectively. TfB was present in a frequency of 0.0059. The frequencies of Gc alleles were found to be 0.4478 for GcIF, 0.3875 for GcIS and 0.1647 for Gc2. The gene frequency of GcIF was rather high in comparison with Iranian and Indian populations.     

Gc subtypes in Finns, Swedes and Swedish Lapps

The group-specific component (Gc) subtypes were determined by isoelectric focusing and immunoblotting. The gene frequencies in the Swedish Lapps were Gc1F = 0.412, Gc1S = 0.367 and Gc2 = 0.221, which was significantly different from the frequencies found in Finns and in the populations of northern and central Sweden (p less than 0.001). The gene frequencies in the Swedish Lapps, although similar to those in Asiatic populations, are probably not reflecting an Asiatic influence, since the accumulated genetic information on the Swedish Lapps suggests that founder effect and genetic drift are to a large extent responsible for the peculiar gene pool of the original Lapp population.     

Gc and PGM subtypes in northern Greece

By isoelectric fucusing, Gc and PGM subtypes were examined in a sample of over 450 Greeks from Thessaloniki and surrounding areas. The gene frequencies are compared with those from other Greek and European samples.     

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.     

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?).     

Gc serum groups in schizophrenia

Gc subtypes were studied by isoelectric focusing in schizophrenic patients and controls. No significant differences between patients and controls were found. The results so far on Gc groups and schizophrenia show no consistent pattern and the significant associations reported have not been confirmed.     

Gc subtypes in some population groups from Israel. Comparison between world population groups and between Jews and non-Jews of the same areas

Results of Gc subtyping on 1,222 Israelis, Arabs and Jews, are summarized and their gene frequencies are analyzed in comparison with available data on Gc subtypes in non-Jews. A discriminant and a cluster analysis demonstrated that in their Gc subtype frequencies European and non-European Jews resemble the populations of the areas where they lived before immigrating to Israel. A possible explanation for this resemblance, which is seen in some and not seen in other genetic markers in Jews, is suggested here to be connected with the function of Gc as a vitamin D-binding protein.     

Gc and Tf subtypes in Greece

PAGIF was used to investigate the distribution of Gc and Tf subtypes in a Greek population sample. The gene frequencies were compared to those reported for other European populations.     

A genetic study of blacks from Trinidad

A series of 171 blacks from Trinidad, West Indies, was studied with respect to haemoglobin types, serum protein systems (Tf and Gc subtypes) and red cell enzyme types (AcPh, 6-PGD, AK, EsD, GLO and PGM1). The average Caucasian admixture was estimated at 25%.     

The effect of Gc genotype on fasting insulin level in Dogrib Indians

Summary The metabolically active form of vitamin D, 1,25-(OH)₂D₃, is involved in the regulation of insulin level. Because the serum group-specific component (Gc) binds vitamin D, it is worth knowing whether differences in basal insulin levels are associated with Gc genotype. Such differences would warrant further investigation to clarify whether selection maintains Gc polymorphism through differential risk of Gc genotypes to diseases that involve insulin. Blood samples were collected in a study designed to address issues in the etiology of non-insulin-dependent diabetes mellitus in Amerindians. Fasting insulin levels and Gc genotype (including subtypes of Gc ₁) were determined for 144 adult Dogrib Indians of the Northwest Territories, Canada. Hierarchical regression of log₁₀ transformed fasting insulin on age and adiposity within each sex showed that age had no effect on insulin level, but adiposity as measured by the body mass index (BMI) had a very highly significant effect. Analysis of covariance of log₁₀ fasting insulin by sex, by Gc genotype and with adjustment for the effects of the covariate, BMI, was very highly significant. All interaction terms in the model were nonsignificant. The only variable that had a significant effect after adjustment for the BMI was Gc genotype (F_4,133=3.71; P=0.007). Covariance analysis was repeated on a subset of the sample (124 people). The reduced data set excluded all individuals who had, on at least one occasion, abnormal response to oral glucose challenge [impaired glucose tolerance (IGT) or noninsulin-dependent diabetes mellitus (NIDDM)]. Again, after correction for the effects of the BMI, only Gc genotype had a significant effect on fasting insulin level (F_4,113=2.61; P=0.040). Homozygotes for Gc 1F-1F had the lowest measures of fasting insulin.     

Gc and transferrin isoelectrofocusing subtypes among Brazilian Indians

A total of 397 persons living in six villages of three Brazilian Indian tribes were studied in relation to the Gc subtypes. The corresponding gene frequencies are more similar between the Gorotire and Caingang than between the Gorotire and the Krahó, despite the considerable geographical distance that separates the villages of these two first tribes and their lignuistic differentiation. An uncommon variant pattern (1C7) was observed in eight Gorotire Indians; it had been described for the first time in a Tibetan sample, furnishing additional evidence on the Asiatic origin of these Indians. The distinct Gc subtype frequencies observed in our main ethnic groups provide an important new tool for anthropological analyses. Tf subtypes were studied among the Caingang only. The frequencies of Tf^C1 and Tf^C2 are similar to those obtained by other researchers in Hessen, Germany.     

Binding of a monoclonal antibody E12 to Gc globulin (vitamin D-binding protein) is inhibited by actin.

A monoclonal antibody, E12, to human Gc globulin was raised in murine somatic cell using purified Gc. The antibody was subtyped IgG2b kappa and had a kd of 3.0 x 10(-8) M for antigen Gc. Monospecificity for Gc was demonstrated by Western blotting of normal human serum using nondenaturing polyacrylamide gel electrophoresis. As judged by ELISA, actin inhibited binding of E12 to Gc in dose-dependent fashion. Affinity chromatography studies further showed that ternary complexes of actin-Gc-E12 were not formed, and actin displaced Gc from Gc-E12 complexes. Proteolytic digestion of Gc with trypsin showed that the monoclonal antibody E12 reacted with the major 30-kDa tryptic fragment containing the amino terminal fragment of Gc, but actin did not react with this fragment. These results indicate that interaction of actin with Gc causes conformational changes which inhibit binding of E12.