Group-specific Component Research Articles

Use of electrophoresis for the determination of protein polymorphisms: application to the study of isolated human populations

Third factor of complements (C3), group specific component (Gc), properdin B factor (Bf), haptoglobin (Hp) and transferrin (Tf) polymorphisms were studied in a mountain communities samples from the Italian-French Alps. Electrophoresis was used to determine the seroprotein systems, since both traditional and high-resolution methods have proved to be valid tools in anthropogenetic investigations. Principal components analysis and maximum likelihood estimation were used to analyse the genetic relationships among populations.

Polymorphism of seroproteins in communities of the Briançon region: comparison with European populations

The present study is an analisis of seroproteins conducted on blood samples of subjects living in mountain communities of the French Western Alps. In particular, the third component of complement (C3), the group specific component (Gc), properdin B factor (Bf), haptoglobin (Hp) and transferrin (Tf) were considered, these being very important markers in human genetics research. The data for these systems are the first results of the biological study of populations of the Western Alps. They add to our otherwise scanty knowledge about the distribution of these polymorphisms in the populations under study. The results were compared with those in the literature on European populations, in order to identify origins and microevolutionary processes, as well as biotransformations related to environmental adaptation.

Use of electrophoresis for the determination of protein polymorphisms: application to the study of isolated human populations

Third factor of complements (C3), group specific component (Gc), properdin B factor (Bf), haptoglobin (Hp) and transferrin (Tf) polymorphisms were studied in a mountain communities samples from the Italian-French Alps. Electrophoresis was used to determine the seroprotein systems, since both traditional and high-resolution methods have proved to be valid tools in anthropogenetic investigations. Principal components analysis and maximum likelihood estimation were used to analyse the genetic relationships among populations.

Vitamin D pathway gene polymorphisms, diet, and risk of postmenopausal breast cancer: a nested case-control study

IntroductionVitamin D receptor (VDR) polymorphisms have been inconsistently associated with breast cancer risk. Whether risk is influenced by polymorphisms in other vitamin D metabolism genes and whether calcium or vitamin D intake modifies risk by genotype have not been evaluated.MethodsWe conducted a nested case-control study within the Cancer Prevention Study II Nutrition Cohort of associations between breast cancer and four VDR single-nucleotide polymorphisms (SNPs), Bsm1,Apa1,Taq1, and Fok1, a poly(A) microsatellite, and associated haplotypes (baTL and BAtS). We also examined one SNP in the 24-hydroxylase gene (CYP24A1) and two in the vitamin D-binding protein (group-specific component [GC]) gene. Participants completed a questionnaire on diet and medical history at baseline in 1992. This study includes 500 postmenopausal breast cancer cases and 500 controls matched by age, race/ethnicity, and date of blood collection.ResultsIncident breast cancer was not associated with any genotype examined. However, women with the Bsm1 bb SNP who consumed greater than the median intake of total calcium (≥902 mg/day) had lower odds of breast cancer compared to women with the Bb or BB genotype and less than the median calcium intake (odds ratio 0.61, 95% confidence interval 0.38 to 0.96; pinteraction = 0.01). Similar interactions were observed for Taq1 (T allele) and the poly(A) (LL) repeat.ConclusionWe found no overall association between selected vitamin D pathway genes and postmenopausal breast cancer risk. However, certain VDR gene polymorphisms were associated with lower risk in women consuming high levels of calcium, suggesting that dietary factors may modify associations by VDR genotype.

Polymorphisme protéique sanguin chez le poney de Mogod de Tunisie

Le poney de Mogod est originaire du nord ouest de la Tunisie. Ses aptitudes physiques lui confèrent une bonne adaptation et utilisation en montagne. Depuis le début du XXe siècle son effectif a subi une réduction considérable. Un plan de relance nécessite une meilleure caractérisation de la race, notamment d’un point de vue génétique. De plus, celle-ci permettrait de rechercher une éventuelle filiation de ce poney avec les autres chevaux de la région. Les systèmes électrophorétiques de l’albumine (Al), du composant GC (Gc), de la postalbumine (Xk), de l’estérase basique (Es), de la transferrine (Tf) et de la préalbumine (Pi) ont été étudiés chez 47 poneys de Mogod par la technique d’électrophorèse en gel de polyacrylamide. Les fréquences alléliques des six systèmes ont été estimées comme suit : AlA : 0,36 ; AlB : 0,64 ; GcF : 1,00 ; XkK : 1,00 ; EsI : 0,64 ; EsG : 0,18 ; EsF : 0,17 ; EsS : 0,01 ; TfD : 0,41 ; TfF2 : 0,31 ; TfH : 0,12 ; PiL : 0,35 ; PiU : 0,22 ; PiR ; PiS : 0,09. Une comparaison entre le polymorphisme protéique sanguin du poney de Mogod et celui des chevaux pur-sang Arabes, Barbes et Arabes-Barbes a été réalisée sur une base bibliographique.

Genetic Markers and Psoriasis in Three Ethnic Populations of Dagestan

Analysis of clinical material obtained from the individuals (49 psoriasis patients and 357 individuals without this disease) representing three ethnic populations of Dagestan (Avars, Dargins, and Kumyks) was performed. Polymorphism of the blood group loci AB0, Rhesus (RH), Kell, P, and Lewis, as well as of the protein-encoding loci for haptoglobin (HP), group-specific component (GC), and the enzymes, including glycosylase (GL01), esterase D (ESD), 6-phosphate dehydrogenase (6PDG), and acid phosphatase (ACP), was studied. It was demonstrated that in the pooled sample of Avars and Kumyks the Lewis system phenotype Le(a-b-) and the RH homozygotes (ee/ee) were statistically significantly more frequent among the psoriasis patients (P = 0.0488 and P = 0.0166, respectively), than among healthy controls of the same ethnic groups. It was suggested that for the pooled sample of Avars and Kumyks, homozygosity for the recessive RH allele (ee/ee) in combination with the Le(a-b-) phenotype, representing homozygosity for recessive allele le, was the risk factor for the development of psoriasis.

Genetic characterization of an isolated alpine population using seroprotein markers: Vallouise (Briançonnais)

The aim of the “Dauphine Project” is to reconstruct, with a wide perspective and multidisciplinary approach, the anthropological history of some mountain populations in both the French and the Italian parts of the Ancient Dauphine. Within the “Dauphine Project”, the present study is an analysis of seroproteins conducted on blood samples of subjects living in Vallouise, small mountain community (Brianconnais); they are male and female adults from families native to the zones for at least two generations. In particular, the third component of complement (C3), the group specific component (Gc) and properdin B factor (Bf) were considered, these being very important markers in human genetics research. The data for these systems are the first results of the biological study of populations of the Western Alps. They add to our otherwise scantly knowledge about the distribution of these polymorphisms in the populations under study. The results were compared with those in the literature on European populations, particularly of the Mediterranean area, in order to identify origins and microevolutionary processes, as well as biotransformations related to environmental adaptation.

Sensitive Automated ELISA for Measurement of Vitamin D-Binding Protein (Gc) in Human Urine

We report a sensitive automated ELISA for measurement of group-specific component (Gc; also known as Gc globulin and vitamin D-binding protein) that detects lower concentrations than any other published method. This new ELISA enables measurement of Gc in human urine. Gc is a 50- to 58-kDa multifunctional plasma protein synthesized mainly by hepatocytes and usually present in plasma in concentrations between 4 and 6 μmol/L. The functions of Gc are diverse. Gc is an important player in the actin-scavenger system, which prevents the harmful consequences of actin in the blood stream during tissue injury. It binds actin monomers with high affinity, and Gc–actin complexes are rapidly cleared from the circulation (1). Gc also has functions in the immune system, acting as a co-chemotactic factor together with complement C5a (2) and, after deglycosylation, as a very potent macrophage-activating factor (Gc-MAF) also capable of activating osteoclasts (3)(4). The name “vitamin D-binding protein” is derived from its ability to bind and transport vitamin D metabolites. Usually, <0.1% of 25-hydroxyvitamin D (25OHD) and <1% of 1,25-dihydroxyvitamin D [1,25(OH)2D] circulate in their free forms (5). Gc is probably also important for the renal activation of 25OHD to 1,25(OH)2D. Mice lacking the multifunctional receptor megalin lose Gc–25OHD complexes in the urine and are deficient in 1,25(OH)2D (6). Thus, there is evidence that, generally, Gc and Gc–25OHD complexes are filtered in the glomerulus and reabsorbed by megalin-mediated endocytosis into the proximal tubular cells, where vitamin D activation takes place. This theory postulates that, under healthy conditions, only trace amounts of Gc should be excreted in the urine, whereas urinary loss of Gc is expected to increase with decreases in the capacity for reabsorption in the proximal tubules. To evaluate the fate of Gc in humans with various kidney diseases, …

Plasma concentrations of 25-Hydroxy-Vitamin D and 1,25-Dihydroxy-Vitamin D are Related to the Phenotype of Gc (Vitamin D-Binding Protein): A Cross-sectional Study on 595 Early Postmenopausal Women

The major transporter of vitamin D metabolites in the circulation is the multifunctional plasma protein Gc, also known as group-specific component, Gc globulin, vitamin D-binding protein, or DBP. There are several phenotypes of Gc, and we examined the influence of Gc phenotype and Gc concentration on vitamin D status. By using isoelectric focusing we identified the Gc phenotype of 595 caucasian recent postmenopausal women enrolled into the Danish Osteoporosis Prevention Study (DOPS). We measured plasma concentration of Gc by immunonephelometry (coefficient of variation [CV] < 5%), 25-hydroxy vitamin D (25OHD) by a competitive protein-binding assay (CV 10%), and 1,25-dihydroxy-vitamin D (1,25(OH)(2)D) by a radioimmunoassay (CV 6--14%), and calculated index as the molar ratio of vitamin concentration divided by Gc concentration. Plasma levels of Gc, 25OHD, 25OHD index, and 1,25(OH)(2)D, but not 1,25(OH)(2)D index, differed significantly between women with different Gc phenotype, being highest in Gc1-1, intermediate in Gc1-2, and lowest in Gc2-2. In multiple regression analysis, Gc concentration was an independent predictor of 1,25(OH)(2)D, whereas Gc phenotype was a significant predictor of 25OHD concentration, even after adjustment for the effects of season, sunbathing habits, skin thickness, use of vitamin supplements, smoking, and body mass index (BMI). Plasma parathyroid hormone (PTH) level did not differ between Gc phenotypes. Despite the fact that more than 60% of the women with Gc phenotype Gc2-2 had plasma 25OHD levels of less than 50 nmol/L none of them had plasma PTH higher than reference limits. Bone mineral content (BMC), Bone mineral density (BMD), and bone markers did not differ between Gc phenotypes. In conclusion, plasma 1,25(OH)(2)D, 25OHD, and 25OHD index are related to Gc phenotype, and we speculate that the thresholds for vitamin D sufficiency differ between Gc phenotypes.

Genetic Analysis of Reproduction in the Buryat Populations

A complex anthropological survey based on population-genetic methods and a study of a wide spectrum of genetic systems (43 alleles from 17 independent loci) was undertaken among 450 Buryat women of post-reproductive age. The results obtained showed the influence of particular genetic markers and their complex on the formation of peculiarities in the reproduction structure of the Buryat population.A sharp increase in phenotype GC 2-2 frequency and the corresponding GC*2 allele of the group-specific component (GC) was established for women groups with burdened obstetric records. These groups are characterized also by a considerable decrease in the observed geterozygosity (Ho) as compared to its expected value (He). Samples including women with multiple pregnancies in the recorded obstetric anamnesis are characterized by a significant increase in the frequency of the rare alleles TF*C3 of the transferrin system and those of PI*Z belonging to the proteinase inhibitor system (a1-antitrypsin) as compared to the control group. The results obtained widened current knowledge about the influence of genetic and environmental components on reproduction processes in human populations.

78 Association of the group specific component (GC) gene polymorphisms with severe cystic fibrosis lung disease

78 Association of the group specific component (GC) gene polymorphisms with severe cystic fibrosis lung disease

Identification of a Region in the Vitamin D-binding Protein that Mediates Its C5a Chemotactic Cofactor Function

The vitamin D-binding protein (DBP), also known as group-specific component or Gc-globulin, is a multifunctional plasma protein that can significantly enhance the leukocyte chemotactic activity to C5a and C5a des-Arg. DBP is a member of the albumin gene family and has a triple domain modular structure with extensive disulfide bonding that is characteristic of this protein family. The goal of this study was to identify a region in DBP that mediates the chemotactic cofactor function for C5a. Full-length and truncated versions of DBP (Gc-2 allele) were expressed in Escherichia coli using a glutathione S-transferase fusion protein expression system. The structure of the expressed proteins was confirmed by SDS-PAGE and immunoblotting, whereas protein function was verified by quantitating the binding of [(3)H]vitamin D. Dibutyryl cAMP-differentiated HL-60 cells were utilized to test purified natural DBP and recombinant expressed DBP (reDBP) for their ability to enhance chemotaxis and intracellular Ca(2+) flux to C5a. Natural and full-length reDBP (458 amino acid residues) as well as truncated reDBPs that contained the N-terminal domain I (domains I and II, residues 1-378; domain I, residues 1-191) significantly enhanced both cell movement and intracellular Ca(2+) concentrations in response to C5a. Progressive truncation of DBP domain I localized the chemotactic enhancing region between residues 126-175. Overlapping peptides corresponding to this region were synthesized, and results indicate that a 20-amino-acid sequence (residues 130-149, 5'-EAFRKDPKEYANQFMWEYST-3') in domain I of DBP is essential for its C5a chemotactic cofactor function.

Female premenopausal fracture risk is associated with gc phenotype.

The phenotype of the vitamin D binding and macrophage activating protein, Gc, is a predictor of premenopausal bone fracture risk, possibly mediated through activation of osteoclasts. This was concluded from a study on 595 Danish perimenopausal women 45-58 years of age (30,040 person years). The multifunctional plasma protein Gc, also known as group-specific component, Gc globulin, or vitamin D binding protein (DBP), has two functions with relation to bone tissue: it is the major carrier protein of vitamin D in the circulation, and deglycosylation converts it into a very potent macrophage- and osteoclast-activating factor (Gc-MAF). There are several phenotypes of Gc, and in this study, we examined the relation between Gc phenotype and bone fragility. By isoelectric focusing we identified the Gc phenotype of 595 white recent postmenopausal women enrolled into the Danish Osteoporosis Prevention Study (DOPS) and identified three groups: Gc1-1 (n = 323), Gc1-2 (n = 230), and Gc2-2 (n = 42). Differences between the three groups were examined with respect to number of fractures before enrollment, BMC and BMD, and various biochemical and clinical parameters, including the concentration of Gc measured by immunonephelometry and the concentration of the macrophage marker soluble CD163 measured by ELISA. The risk of having at least one premenopausal bone fracture (total number of women with fracture = 179) differed significantly (p = 0.017) in women with phenotype Gc1-1 (110/323 = 0.34), Gc1-2 (63/230 = 0.27), and Gc2-2 (6/42 = 0.14). The differences were even more striking (p = 0.005) for fractures caused by low-energy traumas. Using logistic regression, we found the relative risk of premenopausal fracture to be 0.32 (0.13-0.80) in Gc2-2 compared with Gc1-1. We propose that the Gc phenotypes cause differences in osteoclast activity, a theory supported by our finding of lower levels of Gc and of soluble CD163 in women with Gc2-2 compared with Gc1-1.

Association of vitamin D binding protein variants with chronic mucus hypersecretion in Iceland.

Previous studies of vitamin D binding protein (VDBP, also known as group-specific component, Gc, encoded by the GC gene) have implicated two gene variants, GC*2 and GC*1F, as possible contributors with chronic obstructive pulmonary disease (COPD) protection and susceptibility, respectively. The objective of this study was to examine the association of VDBP to different subtypes of COPD. The association of the various GC genotypes to the COPD phenotype was examined in Icelandic COPD patients who were followed by pulmonary physicians at the University Hospital of Iceland. All patients were genotyped for the known alleles of the GC gene. The single nucleotide polymorphisms (SNPs) were identified by a restriction fragment length polymorphism procedure. Study power was estimated based on allele frequencies of the variants, and risk ratios were calculated from the prevalence of genotypes in the affected group divided by its prevalence in the control population. Statistical analyses were performed using the 2-tailed Fisher's Exact Test and chi(2) test, where appropriate. One hundred and two COPD patients and 183 controls, together with 46 asthma patients and 48 patients with chronic mucous hypersecretion (CMH) were examined. The results demonstrate similar allele and genotype frequencies of GC in COPD patients overall and healthy controls. However, there was a higher prevalence of genotypes carrying a GC*1F allele and lower prevalence of genotypes with a GC*2 allele in the CMH patients than in controls. This difference was most notable in the homozygous form: 8.3% vs 1.1% for the GC*1F/*1F, and 0.0% vs 7.6% for the GC*2/*2 genotypes, respectively. When controlled for smoking, only the non-smoking CMH patients demonstrated a significantly altered frequency of the GC*1F/*1F genotype (p = 0.0001). The prevalence of the GC*2/*2 genotype was also significantly lower in patients with bronchial hypersecretion with airflow obstruction compared with the control group (2.9% vs 7.6%). Taken together, these results demonstrate that the GC*1F and GC*2 alleles are associated with sputum hypersecretion in individuals who are at increased risk of developing COPD.

Risk and Severity of COPD Is Associated With the Group-Specific Component of Serum Globulin 1F Allele

The finding that only 15 to 20% of cigarette smokers acquire COPD suggests that there is a genetic predisposition to the disease. Genetic polymorphism of the group-specific component of serum globulin (Gc-globulin), also known as vitamin-D-binding protein, is considered one of the candidates for the susceptibility to COPD. However, the role of Gc-globulin polymorphism in the development of COPD remains inconclusive. s: To determine whether Gc-globulin gene polymorphism plays a role in the development of COPD in the Japanese population, and whether it is associated with the physiologic deterioration in COPD, and its radiologically detectable correlates. Association study. One hundred three patients with COPD and 88 healthy smokers sampled from the Japanese population were genotyped for Gc-globulin by the restriction fragment-length polymorphism method. Based on the results of the genotyping, we investigated the relationship between Gc-globulin polymorphism and a physiologic/radiologic indicator of lung function, namely, the annual decline of FEV(1) (dFEV(1)) in 86 patients with COPD and 21 healthy smokers. Additionally, high-resolution CT parameters such as low-attenuation area percentage (LAA%) and average CT number (mean CT score) were measured in 85 patients with COPD. There was an increased proportion of Gc*1F homozygotes in the patients with COPD (32%) compared with the healthy smokers (17%) [p = 0.01; odds ratio, 2.3; 95% confidence interval, 1.2 to 4.6]. Patients with COPD and the Gc*1F allele showed a larger dFEV(1) (p = 0.01), higher frequency with LAA% > 60% (p = 0.01), and lower mean CT score than patients without this allele (p = 0.03). Gc-globulin polymorphism is significantly associated with susceptibility to COPD, and also with the severity of the disease.

Genetic Diversity of Serum Proteins in Three Subpopulations of the Maria Gond Tribe of Madhya Pradesh, India

The phenotype and allele frequency distribution of group specific component (GC), transferrin (TF), alpha-1-antitrypsin (PI) and apolipoprotein E (APOE) was determined by isoelectric focusing of plasma samples from three subpopulations (Bison Horn Maria of the Kuakonda and Tokapal Block, and Abuj Maria of the Abujmar Hills of the Orchha block) of the Maria Gond tribe of Madhya Pradesh, India. A considerable level of allele frequency variation was observed in these subpopulations, which highlighted social and geographical isolation among them. The average heterozygosity for these IEF subtype systems was high (29-39%) and the gene diversity among these subpopulation groups was of low to moderate range (1.4%). The overall analysis showed that these polymorphisms are useful anthropological markers for micro-evolutionary and genetic structure studies.

Brazilian population data on the polymerase chain reaction-based loci LDLR, GYPA, HBGG, D7S8, and Gc.

Gene and genotype frequencies in relation to the low density lipoprotein receptor (LDLR), glycophorin A (GYPA), hemoglobin G gammaglobin (HBGG), D7S8, and group specific component (Gc) loci were determined in a sample of 344 unrelated individuals (250 whites and 94 mulattoes) living in the city of São Paulo, Brazil. DNA was extracted from 5 mL of peripheral blood obtained from each of the 344 volunteers by the salting-out procedure. Polymerase chain reaction and reverse dot-blot analysis were performed with the Amplitype PM PCR Amplification and Typing Kit (Polymarker Multiplex; Applied Biosystems, Foster City, CA) under conditions recommended by the manufacturer. Estimated allele frequencies in the white sample were in the usual range of that of other United States and European population groups. In any case, genotype distributions for these loci did not deviate significantly from Hardy-Weinberg equilibrium proportions. Only 1 marginally significant (0.01 < P < 0.05) association, between loci HBGG and Gc, was detected in our mulatto sample out of a total of 20 possible pairwise comparisons of the 5 loci for both data sets. Allele frequencies were significantly different (P < 0.001) at the HBGG and Gc loci when the white and mulatto samples were compared. Biologic relationship exclusion probabilities (test powers) were calculated for the data. A Brazilian database has thus been established for the loci LDLR, GYPA, HBGG, D7S8, and Gc, 5 polymerase chain reaction-based loci systems that have been shown to be a useful tool for biologic relationship identification and exclusion.

Rapid detection of GYPA, LDLR, HBGG, D7S8 and GC alleles by real-time fluorescence PCR

We developed the allele-specific TaqMan polymerase chain reaction (AS-TaqMan PCR) and SYBR Green PCR assays for detecting glycophorin A (GYPA), low-density lipoprotein receptor (LDLR), hemoglobin G (HBGG), D7S8 and group-specific component (GC) alleles. We improved the specificity of detecting a nucleotide substitution by introducing the additional mismatches at position 2 (3 in GYPA). The differences between threshold cycle (Ct) values of different genotypes on each of the loci were statistically significantly different. All the genotypes agreed with the results using the AmpliType PM+DQA1 PCR Amplification and Typing kit. The AS-TaqMan PCR and SYBR Green PCR assays are simple, rapid, and accurate, as well as suitable for high-throughput applications in a forensic investigation.

Genetic Variation of Serum Proteins Among the Koch Sub-populations of West Bengal, India

The phenotype and allele frequency dis- tribution of group specific component (GC), transfer- rin (TF), alpha-1-antitrypsin (PI) and Apolipoprotein E (APOE) was determined by isoelectric focusing of plasma samples from three subpopulations (Boro-Deshi- Dinajpur District, Boro-Deshi-Malda District, and ChhotoDeshi-Malda District) of the Koch Scheduled castes of West Bengal. An appreciable level of allele frequency variation was observed in populations, which highlighted social and geographical isolation among these subpopulations and which is also compatible with the ethnohistory of the groups studied. Average het- erozygosity for these IEF subtype systems was high (46- 61%) and gene diversity among these population groups was of low to moderate range (1.5%). Overall analysis showed that these polymorphisms are useful anthro- pological markers for micro-evolutionary and genetic structure studies.

Genetic Variation of Serum Proteins Among the Koch Sub-populations of West Bengal, India

The phenotype and allele frequency dis- tribution of group specific component (GC), transfer- rin (TF), alpha-1-antitrypsin (PI) and Apolipoprotein E (APOE) was determined by isoelectric focusing of plasma samples from three subpopulations (Boro-Deshi- Dinajpur District, Boro-Deshi-Malda District, and ChhotoDeshi-Malda District) of the Koch Scheduled castes of West Bengal. An appreciable level of allele frequency variation was observed in populations, which highlighted social and geographical isolation among these subpopulations and which is also compatible with the ethnohistory of the groups studied. Average het- erozygosity for these IEF subtype systems was high (46- 61%) and gene diversity among these population groups was of low to moderate range (1.5%). Overall analysis showed that these polymorphisms are useful anthro- pological markers for micro-evolutionary and genetic structure studies.