Human sociogenetics

In three cities of Chile (Santiago, Valparaiso, Valdivia) the A allele and phenotype (ABO blood group) are more frequent in the higher socioeconomic strata (SES) and the O allele and phenotype are in the lower ones. This constitutes a structured sociogenetic cline (SGC). The B allele and phenotypes (B+AB) present a rather erratic or contradictory distribution among SES. This SGC was also found in England. The standard interpretation of the origin and maintenance of this SGC in Chile is founded on socio-ethno-historic-cultural and drift factors followed by socioeconomic assortative mating that has occurred since the origin of Chileans by the admixture of Europeans and Amerindians. This interpretation is insufficient to explain the coincidence of the cline in England and Chile, and for some findings in Chile. 1) The A and Rh(-) frequencies of the highest SES in Chile are significantly higher than those found in Europeans. 2) The B gene and phenotypes (with AB) behave differently and in contradiction to the socio-ethno-cultural-historical process. 3) There is a significant interaction of the SGC with gender in Chile and England. There is not at present a putative relationship between ABO and psycho-social factors that could account for this sociogenetic interaction. This SGC seems to be present in societies with a hierarchical organization in relation to power, prestige, ownership, income and life style, and when sampling includes the most extreme SES. It has not been found in two samples from Ireland and in a sample from Chile taken from a public hospital, probably because those variables and conditions were not ascertained.     

DYS19 and DYS199 loci in a Chilean population of mixed ancestry

The current Chilean population originated from admixture between aboriginal populations (Amerindians) and Spanish conquerors of European origin. Consequently, the unions that gave rise to the Chilean population were chiefly between Spanish males and aboriginal females, and not the converse. To test the hypothesis that the Y chromosome of the Chilean population is mainly of Spanish origin, while the other chromosomes are from mixed (European and aboriginal) origin, we studied the DYS19 and DYS199 loci in two samples. One sample was obtained from a high socioeconomic stratum, while a second sample was from a low stratum. We studied male blood donors (N = 187) from Santiago, the capital of the country. Subjects were typed for the autosomal ABO and Rh (locus D) blood groups, and for the Y-linked DYS19 and the DYS199 loci, reported as Y-chromosome haplotypes. The aboriginal admixture was estimated for each genetic marker. The percentage of aboriginal admixture was 38.17% for the ABO system and 31.28% for the Rh system in the low socioeconomic stratum and 19.22% and 22.5%, respectively, in the high stratum. Y-chromosome haplotype frequencies constructed from the DYS19 and DYS199 loci demonstrated that the main haplotypes were DYS19*14/DYS199 C, as is often the case with many European populations, and DYS19*13/DYS199 C. The aboriginal admixture from Y-haplotype frequencies was estimated to be 15.83% in the low socioeconomic stratum and 6.91% in the high stratum. These values are lower than the values found using autosomal genetic markers, and are consistent with the historical background of the population studied. This study highlights the population genetic consequences of the asymmetric pattern of genome admixture between two ancestral populations (European and Amerindian).     

Frequency of the hypervariable DNA loci D18S849, D3S1744, D12S1090 and D1S80 in a mixed ancestry population of Chilean blood donors

Blood donors (N = 150) at San José Hospital (Santiago, Chile) were typed for one VNTR locus (D1S80) and three STR loci (D18S849, D3S1744, D12S1090). A questionnaire was used to determine the socioeconomic level of the donors, because it is known that some genetic markers (e.g., the ABO and Rh groups) are differentially distributed between different socioeconomic strata. This methodology revealed that two of the three socioeconomic strata distinguishable in Santiago were present in our sample of blood donors, with stratum II representing the middle strata and stratum III the low strata. Allele frequency was determined for each locus and socioeconomic stratum, and it was found that the allele distributions of each locus in socioeconomic strata II and III were statistically similar. All loci conformed to the Hardy-Weinberg law and there was no evidence for association between the alleles of the four loci, allelic frequencies being similar to those found in North American Hispanic populations. The results support the view that the analysis of these loci may have useful applications in population genetics as well as in identity tests.     

Brief communication: Molecular characterization of O alleles at the ABO locus in Chilean Aymara and Huilliche Indians

A molecular characterization of alleles O1, O1variant (O1v), and the mutation G542A of the ABO blood group was performed in two Amerindian populations of Chile, the Aymara (n = 84) and the Huilliche (n = 75). In addition, a sample of 82 individuals of Santiago belonging to the mixed Chilean population was typed for comparative purposes. The polymorphisms which allow for molecular differentiation of different alleles of the O blood group were studied in genomic DNA. The mutations G188, G261-, G542A, T646A, and C771T, described for alleles O1, O1v, and G542A, were determined using the PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) technique. All individuals studied were group O homozygotes for the deletion G261-, which defines the O1 alleles. Results obtained indicate that allele O1v exhibits frequencies of 0.65, 0.81, and 0.60 in Aymara, Huilliche, and Santiago populations, respectively. The frequencies of allele O1(G542A) were 0.119, 0.113, and 0.079 in the same populations. Frequencies for alleles O1 and O1v obtained in the Chilean populations studied concur with the results obtained by other authors, respecting the greater frequency of allele O1v as well as with its heterogeneous distribution in aboriginal South American populations. In Chilean populations, Allele G542A exhibits lower frequencies than those described for indigenous populations from Brazil and may be used as an Amerind admixture marker.     

ABO and Rh D polymorphism among Tibetans in India

A study of ABO and Rh D polymorphisms was conducted on 923 Tibetans living in exile in four different places (both high and low altitudes) in India. The frequencies of alleles p, q, and r for the ABO blood group system were found to be 0.1295, 0.2544, and 0.6152, respectively, and for alleles D and d of the Rh blood group system the allele frequencies were 0.9428 and 0.0572, respectively, for the total data. No significant difference was found for the allele frequencies among the four places for the two blood group systems. The allele frequencies were in Hardy-Weinberg equilibrium for the ABO blood group system and show East Asian affinity for the Tibetans.     

A note on the presence of blood groups A and B in pre-Columbian South America

The results of ABO typing in Chilean mummies, a review of published South American paleoserological studies and a systematic discrepancy of admixture estimates based on ABO and Gm genes support the hypothesis that Andean pre-Columbian populations possessed the A (and perhaps the B) gene in small frequencies.     

Genetic variation in Arizona Mexican Americans: estimation and interpretation of admixture proportions

Mexican Americans are a numerous and fast growing ethnic population in the United States. Yet little is known about their genetic structure. Since they are a hybrid, it is of interest to identify their parental populations and to estimate the relative contributions of these groups. This information is relevant to historical, biomedical, and evolutionary concerns. New genetic typings on 730 Arizona Mexican Americans for the HLA-A, HLA-B, ABO, Rh, MNSs, Duffy, Kidd, and Kell loci are presented here and they are used to estimate ancestral contributions. We considered both a dihybrid model with Amerindians and Spaniards as proposed ancestors, and a trihybrid model with Amerindians, Spaniards, and Africans as proposed ancestors. A modified weighted least squares method that allows for linkage disequilibrium was used to estimate ancestral contributions for each model. The following admixture estimates were obtained: Amerindian, 0.29 +/- 0.04; Spaniard, 0.68 +/- 0.05; and African, 0.03 +/- 0.02. The interpretation of these results with respect to Amerindian and Spanish ancestry is straightforward. African ancestry is strongly supported by the presence of a marker of African descent, Fy, despite the fact that the standard error of the estimate is as large as the estimated admixture proportion. An evaluation of the sensitivity of these results to a number of variables is presented: 1) our choices of ancestral allele frequencies, 2) the possibility of selection at HLA and the blood groups, and 3) genetic drift in Mexican Americans.     

Admixture estimates for Caracas, Venezuela, based on autosomal, Y-chromosome, and mtDNA markers

The present Venezuelan population is the product of admixture of Amerindians, Europeans, and Africans, a process that was not homogeneous throughout the country. Blood groups, short tandem repeats (STRs), mtDNA, and Y-chromosome markers have been used successfully in admixture studies, but few such studies have been conducted in Venezuela. In this study we aim to estimate the admixture components of samples from two different socioeconomic levels from Caracas, Venezuela's capital city, compare their differences, and infer sexual asymmetry in the European Amerindian union patterns. Gene frequencies for blood groups ABO and Rh (CDE) and for the STRs VWA, F13A01, and FES/FPS and mtDNA and Y-chromosome haplogroups were studied in a sample of 60 individuals living in Caracas, taken from a private clinic (high socioeconomic level), and 50 individuals, also living in Caracas, drawn from a public maternity clinic (low socioeconomic level). The admixture analysis for the five autosomal markers gives a high European component (0.78) and an almost negligible African sub-Saharan component (0.06) for the high socioeconomic level, whereas for the low socioeconomic level the sub-Saharan, European, and Amerindian components were 0.21, 0.42, and 0.36, respectively. Estimates of admixture based on mtDNA and Y-chromosome markers reveal that the Amerindian contribution to these Caracas samples is almost entirely through females, because the Y-chromosome Amerindian and African sub-Saharan chromosomes found in this study were scarce. Our study reveals that the identification of the grandparents' geographic origin is an important methodological aspect to take into account in genetic studies related to the reconstruction of historical events.     

A re‐examination of the heritability of fertility in the British peerage

Abstract

The gene and phenotype frequencies for the ABO blood groups system were studied in two socioeconomically different subpopulations of Santiago, Chile. The data were taken from the maternity services and blood banks of two hospitals, one serving mainly low socioeconomic classes and the other serving middle and high socioeconomic groups. Results show a clear difference in gene and phenotype frequencies between the two subpopulations, a difference maintained in two generations (mothers and their children). These results reinforce other studies showing that socioeconomic forces have resulted in assortative mating and different genetic subpopulations in Chile.     

Genetic structure of Quechua-speakers of the Central Andes and geographic patterns of gene frequencies in South Amerindian populations

A sample of 141 Quechua-speaking individuals of the population of Tayacaja, in the Peruvian Central Andes, was typed for the following 16 genetic systems: ABO, Rh, MNSs, P, Duffy, AcP1, EsD, GLOI, PGM1, AK, 6-PGD, Hp, Gc, Pi, C3, and Bf. The genetic structure of the population was analyzed in relation to the allele frequencies available for other South Amerindian populations, using a combination of multivariate and multivariable techniques. Spatial autocorrelation analysis was performed independently for 13 alleles to identify patterns of gene flow in South America as a whole and in more specific geographic regions. We found a longitudinal cline for the AcP1*a and EsD*1 alleles which we interpreted as the result of an ancient longitudinal expansion of a putative ancestral population of modern Amerindians. Monmonnier's algorithm, used to identify areas of sharp genetic discontinuity, suggested a clear east-west differentiation of native South American populations, which was confirmed by analysis of the distribution of genetic distances. We suggest that this pattern of genetic structures is the consequence of the independent peopling of western and eastern South America or to low levels of gene flow between these regions, related to different environmental and demographic histories.     

Distribution of the ABO system and Rh factor in Sardinia

The authors examine the genetic structure of the Sardinian population based on the gene frequencies of the ABO blood group system and the Rh factor. The sample, composed of 13,972 individuals, is subdivided on the basis of altitude zones (mountain, internal hills, coastal hills and plains) and by historical-geographic zones. Also examined are the frequencies of a group of communities of different altitude and historical-geographic zones. The results point to genetic heterogeneity within both altitude and historical-geographic zones as well as within the single communities. A distribution gradient is seen for the IA and I0 alleles of the ABO system, namely: mountains, internal hills, coastal hills, plains.     

Erythrocyte and HLA antigens of Atacameño Indians

The present study reports the results of erythrocyte antigen typing for the following systems: ABO, MN, Rh, Kell, Duffy, and Diego in roughly 180 Atacameño Indians from the oasis of Toconao, northern Chile. A subsample was tested for variation at the histocompatibility loci A, B, and C. Results agree with previous findings based on smaller samples. Caucasian admixture of the Atacameños from Toconao was estimated to be 0.056 ± 0.022.     

Malignant melanoma in Chile: different site distribution between private and state patients

Background

The body site location of primary Malignant Melanoma (MM) has been correlated with prognosis and survival. Ethnic, genetics, sun exposure factors are related to the anatomical distribution of MM. Low and high socioeconomic strata in Chile differ in ethnic, genetic and cultural conditions. The purpose of this study was to analyze the anatomical MM distribution in the Chilean population in both strata searching for differences due to their ethno-genetic-cultural differences. Records of 1148 MM, 575cases from state hospitals (Low Socioeconomic Strata, LSS) and 573 cases from private clinics (High Socioeconomic Strata, HSS) were analyzed by body site.

Results

Females from LSS showed a higher number of MM in soles, cheeks, and around the eye area. Females from the HSS showed a higher number of MM in dorsal feet and dorsal hands. Males from LSS showed a higher number of MM in soles, around the eye area, and cheeks. However, males from HSS showed a higher number of MM in the trunk, and in the arms. Acral MM was significantly higher in LSS than in the HSS in both sexes. The Chilean population from the HSS and LSS showed differences in the distribution of MM by site. Furthermore, gender differences in the proportion of MM analyzed by anatomical site are observed in both strata.

Conclusions

Results show evidence that differential genetics factors, sun exposure, or other environmental or cultural factors of both strata may account for these differences.     

Variation in the gene frequencies of three generations of humans from Monterrey, Nuevo León, Mexico

Allele frequencies for the ABO, Rh, MNSs, Duffy, Kidd, Lutheran, P and Lewis blood group systems in 207 persons whose 4 grandparents were born in the Monterrey Metropolitan area (MMA), grouped into 3 generations, were ascertained along with other related population from the MMA, Mestizos from Saltillo, Coahuila and Tlaxcala, and from the populations thought to have contributed to their genetic constitution (native Mexican Indians and Spanish). Genetic admixture and distance estimates were calculated. Gene frequencies of the three generations from MMA are intermediate to those of the ancestral populations, indicating that they are Mestizo but with a genetic structure different from Mestizos of Saltillo and Tlaxcala. Both genetic admixture and distance estimates indicate that the oldest generation exhibits the greatest Spanish influence which decreases in the youngest generation and in the other MMA populations as a result of the immigration from the central states of Mexico.     

Blood groups in Native Americans: a look beyond ABO and Rh

The study presents comparisons between blood group frequencies beyond ABO and Rh blood systems in Native American populations and previously published data from Brazilian blood donors. The frequencies of Diego (c.2561C>T, rs2285644), Kell (c.578C>T, rs8176058), Duffy (c.125A>G, rs12075, c.1−67T>C, rs2814778) and Kidd (c.838A>G, rs1058396) variants in Kaingang (n=72) and Guarani (n=234) populations from Brazil (1990-2000) were obtained and compared with data from these populations sampled during the 1960s and with individuals of different Brazilian regions. Data showed high frequencies of DI*01 and FY*01 alleles: 11.8% and 57.6% in Kaingang and 6.8% and 75.7% in Guarani groups, respectively. The main results indicated: (1) reduction in genetic distance over time of Kaingang and Guarani in relation to other Brazilian populations is suggestive of ongoing admixture; (2) significant differences in some frequencies of blood group markers (especially Diego, Kidd and Duffy) in relation to Native Americans and individuals from different geographical regions of Brazil. Our study shows that the frequency of red blood cell polymorphisms in two Native American groups is very different from that of blood donors, when we evaluated blood groups different from ABO and Rh systems, suggesting that a better ethnic characterization of blood unit receptors is necessary.     

Temporal evolution of the ABO allele frequencies in the Canary Islands: the impact of the European colonization

The indigenous Canary Islands population suffered a strong cultural and genetic impact when they were colonized by Europeans in the fifteenth century. The molecular analysis of the ABO blood group gene on aboriginal and seventeenth to eighteenth century remains confirms the demographic history of the islands depicted by previous archaeological, anthropological, and genetic studies. ABO allele frequencies clearly related Canarian aborigines with North African Berber populations, its most probable source of origin, and is far related to Iberian and to the current population of the archipelago. The historical sample shows a congruent intermediate position testifying already a strong European influence that would go in augment since then to present times, affecting all the islands with the important exception of La Gomera.     

Ethnic communities in Israel: The genetic blood markers of the Babylonian Jews

One hundred eighty-eight Jewish individuals who either they or whose both parents were born in Iraq were typed for 7 blood groups (ABO, MNS, Rh, Kell, Duffy, P and Kidd), 12 red cell enzyme systems and 2 serum proteins. Iraqi Jews are characterized by a high frequency of A (in ABO), N (in MNS), low cde (Rh) and low Hp-1. Several rare electrophoretic variants were encountered: PGM₁ 6-1, PHI 3-1 and PHI 2-1, and an unidentified AK phenotype. No evidence of Negroid admixture was found in their gene pool. Comparisons with results previously obtained in Iraqi Jews show general similarities in frequencies while comparisons with neighboring non-Jewish populations suggest divergence in most systems investigated. The difficulties of assessing relationships on the basis of a few selected differences and the need for careful interpretations of similarities are emphasized.     

ABO blood groups in Chilean and Peruvian mummies. II. Results of agglutination-inhibition technique

ABO blood groups of Peruvian and Chilean mummies were determined with the agglutination-inhibition method. In Peru all ABO blood groups were found in the period from 3000 B.C. to 1400 A.D.; from this period to 1650 only A and O were seen. In Chile no B or AB was noted either in pre-Columbian or Colonial mummies. This confirms the archeological concept that the Chilean Indian was culturally as well as genetically different from the Peruvian Indian. Further studies using other genetic markers are in order, as well as changing certain preconceived notions on blood groups of American Indians.     

Genetic variants of serum butyrylcholinesterase in Chilean Mapuche Indians

We estimated the frequencies of serum butyrylcholinesterase (BChE) alleles in three tribes of Mapuche Indians from southern Chile, using enzymatic methods, and we estimated the frequency of allele BCHE*K in one tribe using primer reduced restriction analysis (PCR-PIRA). The three tribes have different degrees of European admixture, which is reflected in the observed frequencies of the atypical allele BCHE*A: 1.11% in Huilliches, 0.89% in Cuncos, and 0% in Pehuenches. This result is evidence in favor of the hypothesis that BCHE*A is absent in native Amerindians. The frequencies of BCHE*F were higher than in most reported studies (3.89%, 5.78%, and 4.41%, respectively). These results are probably due to an overestimation of the frequency of allele BCHE*F, since none of the 20 BCHE UF individuals (by the enzymatic test) individuals analyzed showed either of the two DNA base substitutions associated with this allele. Although enzymatic methods rarely detect the presence of allele BCHE*K, PCR-PIRA found the allele in an appreciable frequency (5.76%), although lower than that found in other ethnic groups. Since observed frequencies of unusual alleles correspond to estimated percentages of European admixture, it is likely that none of these unusual alleles were present in Mapuche Indians before the arrival of Europeans.     

The origin of the cultivated tetraploid potato based on chloroplast DNA

Summary By using restriction enzyme analysis of chloroplast DNA, a geographical cline from the Andean region to coastal Chile was found for the tetraploid potato (Solanum tuberosum). This supports the Andean origin of Chilean ssp. tuberosum. One of the relic cultivars of the early introduction of potato to Europe had ssp. andigena type chloroplast DNA. Its derivatives were largely lost in the mid-19th century due to the late blight epidemic and were replaced by ssp. tuberosum originally introduced from Chile. Therefore, the present common potato has the same type chloroplast DNA as Chilean ssp. tuberosum.