G-6-PD polymorphism and racial admixture in the Cuban population

Summary Esterase D phenotypes were determined in 1082 non-related individuals from the western region of Germany by agarose-gel electrophoresis. Gene frequencies were compared with previous data and all European populations studied so far agreed with the Hardy-Weinberg equilibrium. Mean gene frequencies for Europeans are: EsD ¹ 0.8888, EsD ² 0.1112.     

G-6-PD polymorphism and racial admixture in the Cuban population.

The frequencies of the Gd-A, Gd-A- and Gd-B alleles have been estimated in a random sample of 455 female and 405 male high school students from Habana. The estimates of the Negro and Caucasian relative contributions to the present genetic make-up of the Habana population, based on these gene frequencies, are 0.20 and 0.80 respectively.     

Glyoxalase I polymorphism in Belgium

The phenotypes of red cell glyoxalase I (EC 4.4.1.5) were determined by cellogel electrophoresis in 750 Belgian persons. The gene frequencies found were 0.432 for GLO1 and 0.568 for GLO2.     

Glyoxalase I 'null' allele in the Polish population

A silent allele of red-cell glyoxalase I was found in three generations of a Polish family.     

Glyoxalase I polymorphism in Catalonia (Spain)

Blood samples from two Catalonian populations (North-East of Spain) were analysed for glyoxalase (GLO) I polymorphism. Gene frequencies of GLO1 (0.46 and 0.41) are comparable to those reported for Central-European Caucasoid populations.     

Glyoxalase I polymorphism in South African Bantu-speaking Negroids

Summary The newly described genetic polymorphism of glyoxalase I (GLO) is studied in seven ethnically defined Negroid samples from South Africa (total: n=843). The allele frequencies between the different Negroid samples studied vary only marginally. However, the allele frequency of GLO¹ for the South African Negroid samples combined (i.e., p=0.259), is highly significantly lower than that for Caucasoid samples.Supported by the Deutsche Forschungsgemeinschaft (DFG), Bonn-Bad GodesbergSupported by a research fellowship (1975/76) awarded by the Alexander-von-Humboldt-Stiftung, Bonn-Bad Godesberg     

Blood polymorphisms and racial admixture in two Brazilian populations

One thousand individuals from the southern population of Porto Alegre and 760 from the northeastern city of Natal were studied in relation to 12 and 8 genetic systems, respectively. The data thus gathered were used in different ways to estimate quantitatively the ethnic composition of individuals from these communities. More than half of the genes present in individuals classified as Black in Porto Alegre may be of White origin, while the Whites from this city have 8% of African alleles. The estimated degree of admixture in persons identified as White or Mixed in Natal is not much different among themselves. The ancestry of the total sample can be characterized as 58% White, 25% Black, and 17% Indian.     

Gm allotypes and racial admixture in two Brazilian populations

Summary The Gm types of 515 inhabitants of Belém and 395 inhabitants of Porto Alegre, Brazil were studied in an attempt to quantitatively estimate ethnic parental contributions. The people from Belém can be characterized as 24% black, 22% Indian, and 54% Caucasian. The Porto Alegre blacks seem to have inherited as much as 53% of their genes from Caucasian ancestors, while the whites living there have inherited 8% of their genes from African ancestors. The admixture values obtained for Belém are very similar if just the Gm system is considered or it plus seven other loci are considered, emphasizing the high efficiency of the Gm markers in such analyses.     

Body fat and racial genetic admixture are associated with aerobic fitness levels in a multiethnic pediatric population

Aerobic fitness and adiposity are each independently associated with health outcomes among children, although the relationship between these two variables is unclear. Our objectives were to evaluate (i) the association of adiposity with aerobic fitness using objectively measured levels of percent body fat, compared to BMI as a percentile proxy for adiposity while controlling for genetic admixture, and (ii) the congruence of BMI categories with high and low body fat categories of objectively measured percent body fat. Participants were 232 African-American (AA), European-American (EA), and Hispanic-American (HA) children aged 7-12 years (Tanner stage <3). Aerobic fitness was measured via a submaximal indirect calorimetry treadmill test (VO(2-170)), and physical activity levels with accelerometry. Genetic admixture estimates were obtained using 140 genetic ancestry informative markers to estimate European, African, and Amerindian admixture. Fat mass was determined using dual-energy x-ray absorptiometry (DXA). Children were classified into a low body fat group (<25% in males, <30% in females) or a high body fat group based on their percent body fat; children were also categorized according to BMI percentile. Children in the low body fat group had significantly higher aerobic fitness (P < 0.05) regardless of BMI percentile classification. Higher African genetic admixture was associated with lower aerobic fitness (P < 0.05), while physical activity was positively associated with fitness (P < 0.01). In conclusion, aerobic fitness levels differ by percent body fat and genetic admixture irrespective of BMI classification, and such differences should be taken into account when evaluating outcomes of health interventions.     

HLA class I polymorphism in the Albanian population

The HLA class I polymorphism was studied in a sample of the Albanian population. Ninety-three unrelated healthy Albanians were typed for HLA-A, -B and -Cw antigens by standard microlyphocytotoxicity test. The antigens with the highest frequencies were: HLA-A2 (34.4%), A3 (14.5%) and A1 (12.4%); B51 (19.3%), B35 (12.4%) and B18 (10.2%); Cw4 (16.2%), Cw7 (16.2%) and Cw6 (10.8%). The HLA haplotypes with high frequency in Albanians included A2-B51 (4.3%), A2-B18 (2.4%), A2-B35 (2.4%), Cw4-B35 (7.6%), and Cw7-B18 (6.5%), which are not significantly different from the other neighboring populations. Low frequency of HLA-A1-B8 haplotype (1.1%) is noted in the Albanian population. The frequency of HLA-B27 antigen (1.1%) is one of the lowest frequencies observed in Caucasians. Such results are important in studies of HLA-A1-B8, HLA-B27 and disease associations. These findings should be also useful in understanding the origin of Albanians, representing a base for future studies about HLA polymorphism in the Albanian population.     

DNA diversity and population admixture in Anatolia

The Turkic language was introduced in Anatolia at the start of this millennium, by nomadic Turkmen groups from Central Asia. Whether that cultural transition also had significant population-genetics consequences is not fully understood. Three nuclear microsatellite loci, the hypervariable region I of the mitochondrial genome, six microsatellite loci of the Y chromosome, and one Alu insertion (YAP) were amplified and typed in 118 individuals from four populations of Anatolia. For each locus, the number of chromosomes considered varied between 51-200. Genetic variation was large within samples, and much less so between them. The contribution of Central Asian genes to the current Anatolian gene pool was quantified using three different methods, considering for comparison populations of Mediterranean Europe, and Turkic-speaking populations of Central Asia. The most reliable estimates suggest roughly 30% Central Asian admixture for both mitochondrial and Y-chromosome loci. That (admittedly approximate) figure is compatible both with a substantial immigration accompanying the arrival of the Turkmen armies (which is not historically documented), and with continuous gene flow from Asia into Anatolia, at a rate of 1% for 40 generations. Because a military invasion is expected to more deeply affect the male gene pool, similar estimates of admixture for female- and male-transmitted traits are easier to reconcile with continuous migratory contacts between Anatolia and its Asian neighbors, perhaps facilitated by the disappearance of a linguistic barrier between them.     

Molecular characterization of HbH disease in the Cuban population

Summary Molecular characterization of the -thalassemia mutations present in nine HbH subjects from Cuba was achieved by digestion with Bam HI, Bgl II, and Apa I and hybridization with - and -specific probes. The results show that the molecular basis of the genetic defect is quite homogeneous, all the subjects carrying the –^3.7 type I/--^SEA genotype. Variations are observed in the size of the polymorphic fragments.     

Glyoxalase I in regenerating mouse liver exposed to carcinogens

Glyoxalase I is the first component of glyoxalase system which is involved in detoxification of alpha-ketoaldehydes and converts them to nontoxic substances. This study reports changes in Glyoxalase I activity in relation to DNA synthesis in regenerating liver treated with two polycyclic aromatic hydrocarbons - 7,12-dimethylbenz (a) anthracene and benzo(a)pyrene. Livers after partial hepatectomy show consistent increase in Gly. I which reaches to its peak at 24 hr after surgery. [3H]Thymidine incorporation into DNA also follows the same trend as does Gly. I in regenerating liver. Both the carcinogens have significantly reduced the activity of Gly. I and DNA biosynthesis when compared with untreated partially hepatectomized control livers. The study reveals that though regenerating liver has been considered as an experimental model for neoplasia, unlike tumors (where Gly. I is either absent or in undetectable quantities) it possesses more Gly. I than in normal liver. On the other hand, preneoplastic liver during initiation (in regenerating liver treated with carcinogens, initiation is expected to occur) has very low activity. This suggests that Gly. I is not only involved in controlling growth but possibly is involved in some other phenomenon which is somehow depressed in preneoplastic and cancerous tissues.     

HLA class I and class II polymorphism in the population of Rijeka,Croatia

The aim of the study was to examine frequencies of HLA-A, -B, -DR antigens and haplotypes in population of Rijeka and to compare them with general Croatian and European populations. The subjects were 117 unrelated healthy blood donors. The antigens with the highest frequencies were: A2 (27.2%), A9 (16.3%), B5 (14.8%), B12 (11.8%), B18 (11.8%), DR5 (21.6%) and DR6 (13.8%). Comparison of HLA antigens frequencies has shown statistically significant difference in 1 antigen with Croatian population and in 8 antigens with European population. The HLA haplotypes with high frequencies included HLA-A2, B5 (6.84%), HLA-A2, B12 (6.84%), HLA-A2, B18 (6.84%), HLA-B12, DR2 (9.78%) and HLA-B18, DR5 (6.84%). The antigen B5 showed strongest association with DR5 (6.41%; LD = 1.30) as in general Croatian and in some European populations. The results have shown great diversity of HLA haplotypes in Rijeka population which can be the result of admixture with neighborhood immigrating populations during the history.     

Genetic admixture and population substructure in Guanacaste Costa Rica

The population of Costa Rica (CR) represents an admixture of major continental populations. An investigation of the CR population structure would provide an important foundation for mapping genetic variants underlying common diseases and traits. We conducted an analysis of 1,301 women from the Guanacaste region of CR using 27,904 single nucleotide polymorphisms (SNPs) genotyped on a custom Illumina InfiniumII iSelect chip. The program STRUCTURE was used to compare the CR Guanacaste sample with four continental reference samples, including HapMap Europeans (CEU), East Asians (JPT+CHB), West African Yoruba (YRI), as well as Native Americans (NA) from the Illumina iControl database. Our results show that the CR Guanacaste sample comprises a three-way admixture estimated to be 43% European, 38% Native American and 15% West African. An estimated 4% residual Asian ancestry may be within the error range. Results from principal components analysis reveal a correlation between genetic and geographic distance. The magnitude of linkage disequilibrium (LD) measured by the number of tagging SNPs required to cover the same region in the genome in the CR Guanacaste sample appeared to be weaker than that observed in CEU, JPT+CHB and NA reference samples but stronger than that of the HapMap YRI sample. Based on the clustering pattern observed in both STRUCTURE and principal components analysis, two subpopulations were identified that differ by approximately 20% in LD block size averaged over all LD blocks identified by Haploview. We also show in a simulated association study conducted within the two subpopulations, that the failure to account for population stratification (PS) could lead to a noticeable inflation in the false positive rate. However, we further demonstrate that existing PS adjustment approaches can reduce the inflation to an acceptable level for gene discovery.     

Detecting ancient admixture in humans using sequence polymorphism data

A debate of long-standing interest in human evolution centers around whether archaic human populations (such as the Neanderthals) have contributed to the modern gene pool. A model of ancient population structure with recent mixing is introduced, and it is determined how much information (i.e., sequence data from how many unlinked nuclear loci) would be necessary to distinguish between different demographic scenarios. It is found that approximately 50-100 loci are necessary if plausible parameter estimates are used. There are not enough data available at the present to support either the "single origin" or the "multiregional" model of modern human evolution. However, this information should be available in a few years.