Genetic uniqueness of the Waorani tribe from the Ecuadorian Amazon.

South America and especially the Amazon basin is known to be home to some of the most isolated human groups in the world. Here, we report on a study of mitochondrial DNA (mtDNA) in the Waorani from Ecuador, probably the most warlike human population known to date. Seeking to look in more depth at the characterization of the genetic diversity of this Native American tribe, molecular markers from the X and Y chromosomes were also analyzed. Only three different mtDNA haplotypes were detected among the Waorani sample. One of them, assigned to Native American haplogroup A2, accounted for more than 94% of the total diversity of the maternal gene pool. Our results for sex chromosome molecular markers failed to find close genetic kinship between individuals, further emphasizing the low genetic diversity of the mtDNA. Bearing in mind the results obtained for both the analysis of the mtDNA control region and complete mitochondrial genomes, we suggest the existence of a 'Waorani-specific' mtDNA lineage. According to current knowledge on the phylogeny of haplogroup A2, we propose that this lineage could be designated as subhaplogroup A2s. Its wide predominance among the Waorani people might have been conditioned by severe genetic drift episodes resulting from founding events, long-term isolation and a traditionally small population size most likely associated with the striking ethnography of this Amazonian community. In all, the Waorani constitute a fine example of how genetic imprint may mirror ethnopsychology and sociocultural features in human populations.

Microsatellites and Alu elements from the human MHC in Valencia (Spain): analysis of genetic relationships and linkage disequilibrium.

Two different sets of noncoding markers (microsatellites and Alu elements) from the human chromosome six were analysed in 106 individuals from Valencia (Spain), with the aim of exploring the effect of evolutionary forces on the genetic variability of the major histocompatibility complex (MHC) and assessing the potential usefulness of these genetic loci in phylogenetic studies. Linkage disequilibrium (LD) analyses revealed statistically significant associations among markers located in the MHC class I region, and also between the microsatellite D6S2792 and several genetic loci from MHC class I, II and III regions. Results of the Ewens-Watterson test indicated that only D6S2792 showed significant departure from selective neutrality. Despite the paucity of haplotype data in the literature, results of the phylogenetic analyses at world scale (Alu elements) showed that the genetic relationships of Valencia were mainly determined by the ethnic ancestry of the populations considered, whereas at European scale (microsatellites) population affinities were strongly influenced by geography. Our findings suggest that noncoding markers from the MHC such as Alu and microsatellite loci might have a potential value as lineage (ancestry) markers in investigations into evolutionary, medical and forensic perspectives.

Genetic variability in autochthonous Basques from Guipuzcoa: a view from MHC microsatellites.

Five short tandem repeats (STRs) located at human chromosome 6 were analysed in 97 autochthonous Basques from Guipuzcoa (northern Spain), with the aim of assessing the genetic relationships of Basques at a European scale, based on the variability of the major histocompatibility complex (MHC) region, and comparing the phylogenetic information obtained from STRs, and from HLA class I genes (HLA-A and HLA-B) for the same set of European populations. The integrative approach was focused on D6S265 and D6S2792, according to availability of population databases. F(ST) genetic distances obtained from STRs and from HLA loci were very similar, thereby describing a comparable pattern of genetic structuring among the European populations. These findings were supported by results of the Mantel test of matrix correspondence (r = 0.796, P = 0.0022) and by significant correlations between the first two F(ST) eigenvectors of STRs and HLA genes. Coinciding with previous phylogenetic studies, Basques showed substantial genetic differentiation within the European context, probably as a result of the impact of random genetic drift and high inbreeding levels for extended periods of isolation even from adjacent populations. Analysis of the geographical distribution of the allele frequencies revealed a great number of latitudinal frequency clines in both the MHC STRs and the HLA class I genes, which supports the notion of the post-glacial resettlement of Europe being a crucial factor in the genetic make-up of Europeans. Our results indicate that analysing the genetic variability of MHC microsatellites could be a suitable strategy in evaluating the role of evolutionary forces such as natural selection (because of genetic hitchhiking effect), genetic drift and gene flow in the maintenance of polymorphism at the MHC region, because STRs can efficiently complement the genetic information obtained from HLA genes.

Mitochondrial DNA haplogroup diversity in Basques: a reassessment based on HVI and HVII polymorphisms.

This study provides a more complete characterization of the mitochondrial genome variability of the Basques, including data on the hypervariable segment HVII of the D-loop region, which remains relatively unknown. To that end, genomic DNA from 55 healthy men living in the Arratia Valley (Biscay province) and the Goiherri region (Guipúzcoa province) was examined by direct sequencing. Three-generation pedigree charts were compiled to ensure the collection from autochthonous individuals. The most notable findings emerging from the analysis of haplogroup composition are: (i) lack of U8a mitochondrial lineage, a rare subhaplogroup recently identified in Basques and proposed as a Paleolithic marker, (ii) low frequency of haplogroup V, which conflicts with results of earlier analyses describing high frequencies in southwestern Europe, and (iii) high frequency of haplogroup J, especially subhaplogroups J1c1 and J2a. The frequency of haplogroup J does not coincide with previous mtDNA studies in present-day Basques, but is congruent with frequencies found in prehistoric and historic Basque populations. In explaining divergence in haplogroup composition between modern Basque samples, we hypothesized spatial heterogeneity promoted by population fragmentation due to extreme limitation of dispersal opportunities during the Pleistocene glaciations. Similarities between extinct and extant Basque populations as for the high frequency of lineage J, as well as the abundance of this haplogroup in northern Spain endorse a shift in the focus of attention of mtDNA analysts. A refined dissection of haplogroup J might provide more solid evidence about the process of postglacial recolonization of Europe, and thus about the shaping of the European gene pool.

Autosomal microsatellite variability of the Arrernte people of Australia.

The genomic diversity of the Arrernte people of Australia or caterpillar people was investigated utilizing 13 autosomal short tandem repeat (STR) markers. Significant departures from Hardy-Weinberg equilibrium were detected at the D18S51, TPOX and CSF1PO loci, which persisted after applying the Bonferroni correction. Gene diversity values oscillate between 0.6302 (CSF1PO) and 0.8731 (D21S11). Observed heterozygosity (Ho) ranges from 0.2632 (D18S51) to 0.8333 (vWA) and is lower than the expected heterozygosity (He) for 12 of the 13 loci analyzed. The genetic relationships of the Arrernte with Middle Eastern, East Asian, South Asian and Indian populations were analyzed by distance-based methods, including Neighbor-Joining trees and nonmetric multidimensional scaling. In addition, the genetic contribution of the populations included in the analysis to the Arrernte gene pool was estimated utilizing weighted least square coefficients. Although the Arrernte population exhibits a remarkable level of genetic differentiation, results of the phylogeographic analyses based on autosomal microsatellite data suggest a certain degree of genetic relatedness between the Arrernte tribe of Australia and populations from the Indian subcontinent. In contrast, the STR diversity analyses failed to detect substantial East Asian contribution to the genetic background of the Arrernte group.

Polymorphic Alu insertions and the genetic structure of Iberian Basques.

Eight Alu sequences (ACE, TPA25, PV92, APO, FXIIIB, D1, A25 and B65) were analyzed in two samples from Navarre and Guipúzcoa provinces (Basque Country, Spain). Alu data for other European, Caucasus and North African populations were compiled from the literature for comparison purposes to assess the genetic relationships of the Basques in a broader geographic context. Results of both MDS plot and AMOVA revealed spatial heterogeneity among these three population clusters clearly defined by geography. On the contrary, no substantial genetic heterogeneity was found between the Basque samples, or between Basques and other Europeans (excluding Caucasus populations). Moreover, the genetic information obtained from Alu data conflicts with hypotheses linking the origin of Basques with populations from North Africa (Berbers) or from the Caucasus region (Georgia). In order to explain the reduced genetic heterogeneity detected by Alu insertions among Basque subpopulations, values of the Wright's F(ST )statistic were estimated for both Alu markers and a set of short tandem repeats (STRs) in terms of two geographical scales: (1) the Basque Country, (2) Europe (including Basques). In the Basque area, estimates of Wahlund's effect for both genetic markers showed no statistical difference between Basque subpopulations. However, when this analysis was performed on a European scale, F(ST) values were significantly higher for Alu insertions than for STR alleles. From these results, we suggest that the spatial heterogeneity of the Basque gene pool identified in previous polymorphism studies is relatively recent and probably caused by a differential process of genetic admixture with non-Basque neighboring populations modulated by the effect of a linguistic barrier to random mating.

Genetic position of Valencia (Spain) in the Mediterranean basin according to Alu insertions.

In this work, eight human-specific Alu insertion polymorphisms (ACE, TPA25, PV92, APO, FXIIIB, D1, A25, and B65) were typed in 106 unrelated healthy individuals born in the province of Valencia (Spain), with the aim of analyzing the genetic relationships between this region of the Iberian Peninsula and other Mediterranean populations. To that end, Alu data on Eastern European, Western European, and North African populations were compiled from previous studies. The genetic information was stressed by means of genetic distances (R matrix method), nonmetric multidimensional scaling (MDS) and analyses of molecular variance (AMOVA). In Valencia, the most common Alu insertion was APO (0.940), and the least frequent was A25 (0.104). The average gene diversity (GD) computed for the sample examined was comparatively high (0.382). The insertion frequencies estimated for the eight Alu markers were very similar to the mean frequencies calculated for the whole set of populations included in the study, suggesting the hybrid nature of the Valencia's gene pool. MDS and AMOVA results generated from Alu data reveal that the Mediterranean has acted as a strong genetic boundary between the north (Europe) and the south (Northern Africa), resulting in significant gene diversity between the populations of the two regions. Restricted exclusively to the European scope, we suggest the possibility that the Mediterranean could have also acted as a migratory passageway, propitiating the dissemination of cultures and genes between the east and west of Europe and giving rise to some homogenization of gene frequencies among coastal dwelling populations.

Allelic frequencies of 13 STR loci in autochthonous Basques from the province of Vizcaya (Spain).

Allelic frequencies of 13 STR loci (D3S1358, VWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D16S539, TH01, TPOX, CSF1PO, and D7S820) were estimated from a sample of 73 unrelated healthy donors natives of the Spanish Basque province of Vizcaya. These STR loci constitute the core of polymerase chain reaction (PCR)-based DNA genetic markers in the US Combined DNA Index System (CODIS). All STR loci analysed met Hardy-Weinberg expectations. Based upon the allelic frequencies, forensically important parameters including gene diversity (GD), polymorphism information content (PIC) and power of discrimination (PD) were calculated.

Genetic polymorphism and linkage disequilibrium of the HLA-DP region in Basques from Navarre (Spain).

In this work, a sample of 116 individuals from an autochthonous Basque population (northern Navarre, Spain) was typed at the DNA level for HLA-DPA1 and HLA-DPB1 loci, with the aim of analysing the genetic polymorphism and the linkage disequilibrium (LD) of the HLA-DP region. In this Basque subpopulation, the most frequent alleles were *0103 (0.767) and *0201 (0.185) for DPA1 locus, whereas for DPB1 locus the *0401 allele was predominant (0.307). Accordingly, the most frequent haplotype was DPA1*0103-DPB1*0401 (0.300), which showed a significant LD. However, the haplotypes that most differentiated the sample of Navarre from other worldwide populations already analysed were DPA1*0105-DPB1*1901 (0.011) and DPA1*0201-DPB1*7601 (0.021), both of which showed a strong LD. Analysis of the relationships between populations based on data provided by HLA-DPA1 and HLA-DPB1 loci revealed a high genetic affinity between the Basque samples (North Navarre and Guipúzcoa), which, in turn, tend to plot separately from the remaining European populations. Gene frequency clines for DPB1*01, DPB1*04 and DPB1*11 alleles among European populations are reported for the first time. These alleles showed maximum values of F(ST) (0.033, 0.034 and 0.025, respectively). Various evolutionary forces were considered in discussing the origin of the spatial structuring of the gene frequencies: (i) gene flow, argued from the hypotheses of Post-glacial recolonization from southern Europe or the demic diffusion of farmers from the Near East into Europe, and (ii) the existence of selective pressures that could have generated genetic microdifferentiation.

Relationship between somatotype and blood pressure in a group of institutionalized Venezuelan elders.

BACKGROUND: Somatotype, as an indirect measure of estimating body composition, provides an easy and comprehensive picture of body shape. Multiple investigations have shown the existence of an association between somatotype components and cardiovascular disease. OBJECTIVE: The aim of the present study was to examine the association of somatotype with blood pressure during ageing. METHODS: The Heath-Carter anthropometric somatotype and both systolic (SBP) and diastolic (DBP) blood pressures were recorded. The sample included 809 healthy institutionalized elders (370 males and 439 females) from geriatric units in Caracas, Venezuela. Ages ranged from 60 to 102 years. Product-moment correlation coefficients between somatotype components and both blood pressure readings were calculated. Principal component analysis and homogeneity analysis by means of alternative least squares tests were also performed. RESULTS: Females were more endomorphic and mesomorphic than males. Males were more ectomorphic than females. SBP showed a downward tendency with age in males, while in females the tendency was for the SBP to increase. Correlations among variables were from low to moderate and ranged from -0.37 to +0.34 in males, and from -0.18 to +0.32 in females. Correlations tended to be stronger in the younger age group and differences between sexes were found. A negative tendency in the correlation between ectomorphy and both SBP and DBP was found, except for the oldest age group, for which the correlation was positive. Endomorphy and mesomorphy showed a stable correlation pattern with blood pressure in males, while in females this pattern was more irregular and less consistent. CONCLUSION: Individuals with high levels of SBP and DBP had mean somatotypes, which were similar to those of other male groups characterized by myocardial infarct, coronary heart disease and the risk of hypertension, indicating that these somatotypes may be associated with cardiovascular risk factors. In particular, our results indicate that individuals who present a cardiovascular risk profile are more endomorphic and mesomorphic and less ectomorphic than those with a lower cardiovascular risk profile.

HLA-DQA1 polymorphism in autochthonous Basques from Navarre (Spain): genetic position within European and Mediterranean scopes.

In this work, a sample of 112 individuals from an autochthonous Basque population (Northern Navarre, Spain) were typed at the DNA level for the HLA-DQA1 locus, with the aim of characterizing its polymorphism and analyzing the genetic relationships of Basque Navarrese with other Caucasian populations. Northern Navarre is a neighboring area with Guipúzcoa, a province located in the core of the Basque territory having the highest proportion of Basque-speakers. In Navarrese population, the most frequent alleles were DQA1*01 (0.375) and DQA1*02 (0.259). Frequency clines for both DQA1*0103 allele and DQA1*04* allele cluster (including DQA1*0401, DQA1*0501 and DQA1*0601) among the European and Mediterranean populations considered are reported for the first time. Furthermore, a spatial structuring previously described for DQA1*02 allele is corroborated. The information provided by the highly polymorphic HLA-DQA1 locus was stressed by using genetic distances and non-metrical multidimensional scaling (MDS). The analysis of genetic relationships among populations showed a high genetic affinity between the Basque subpopulations of Northern Navarre and Guipúzcoa, which in turn tended to plot separately from the remaining European and Mediterranean populations. In the same way, the Basques showed no clear relationship to North African populations, as postulated in several previous HLA studies. The observed genetic heterogeneity seems to be conditioned by the high frequencies of the DQA1*02 allele in Basques from Guipúzcoa and North Navarre. These two subpopulations seem to show low levels of admixture with other non-Basque neighboring populations, probably because of their deeply rooted ethnicity and the existence of a linguistic barrier to random mating.

Inbreeding and demographic transition in the Orozco Valley (Basque Country, Spain).

Inbreeding in the Orozco Valley (Basque Country, Spain) between the 18th and 20th centuries was investigated on the basis of ecclesiastical dispensations and surname lists. The variations over time are very similar to those observed elsewhere in Europe, with a major increase in the coefficient of inbreeding in the late 19th and early 20th centuries. This is due mainly to an increase in marriages between first cousins. A highly marked decrease in inbreeding is observed during the 20th century. The secular trends described by the coefficient calculated on the basis of dispensations and by that calculated on isonymy are very similar. The nonrandom component of isonymy reveals a selective search for a related spouse during the period of maximum inbreeding. These results are associated with the process of demographic transition which affected European populations as a whole in the 19th century, resulting in a greater availability of kin among potential mates and thus enabling inbreeding to increase to levels far higher than those observed for earlier centuries.

An insight into recent consanguinity within the Basque area in Spain. Effects of autochthony, industrialization and demographic changes.

BACKGROUND: The importance of studying the genetic kinship of those human groups characterized by a deeply rooted ethnicity has traditionally been and still is an interesting goal of anthropological and population genetic studies. However, only a few surveys have aimed to learn about the impact of industrial development on the consanguinity of these populations and even those have concentrated on industrialized regions. This approach is worth analysing in Spain, where industrialization was late in relation to other western European countries. AIM: In this work we analyse the characteristics of inbreeding in Guipúzcoa from 1951 to 1995. This Basque province underwent industrial and tourist development earlier than other Spanish regions. It has the highest density of Basque speakers and has always occupied a central position within the map of distribution of the Basque language. Guipúzcoa is geographically placed in the core of the Basque area. SUDJECTS AND METHODS: Data on consanguineous marriages recorded in the province of Guipúzcoa between 1951 and 1995 were taken from Roman Catholic dispensations stored in the Diocesan Archives of San Sebastián, the province's capital city. Over the whole time period, a total of 1152 consanguineous marriages were registered. RESULTS: The high frequencies of first cousin (M22) (F = 1/16) and uncle-niece, aunt-nephew (M12) (F = 1/8) consanguineous marriages distinguish Guipúzcoa from the rest of Iberian populations. The M22/M33 ratio (with M33 being second cousins) has never dropped below 0.67, which represents a significant deviation from the expectation value of 0.25. When consanguineous marriages are classified according to marriage partner birthplaces interesting results emerge. Provincial endogamy shows the highest consanguinity rates (57%) and the proportion of M22/M33 is also rather high (0.63). However, a major contribution to the consanguinity levels and mean inbreeding coefficient recorded in Guipúzcoa over recent decades has been made by immigrant relative groups coming from other geographical areas of Spain. In this segment of population the observed M22/M33 rates are 1.44. CONCLUSIONS: This study shows again how important preferentiality (or avoidance) is in human consanguinity, and also how human groups, in spite of being spatially settled in the same territory, present differential attitudes for given consanguinity patterns.