Beta‐globin gene cluster haplotypes as evidence of African gene flow to the northeastern coast of Venezuela

In order to study the origin of mutation HBB*S in Sucre and Anzoátegui states and the genetic affinities of these Venezuelan populations with other human groups, the β‐globin gene cluster haplotypes were determined for 28 sickle cell and/or S‐beta thalassemia patients and for 37 individuals with normal hematological parameters. Bantu, Benin, Senegal, and atypical haplotypes were identified in 50%, 36%, 2%, and 12% of the HBB*S chromosomes, respectively. Similar results have been published for Venezuelan patients from the central states, but a different trend is shown in a publication based on a group of patients from different regions of the country. For HBB*A, haplotype 2 (+ ? ? ? ?), characteristic of non‐African groups, was the most common (39%), followed by haplotype 3 (? ? ? ? +) of African origin, and haplotype 6 (? + + ? +), also typical of non‐Africans. The results reveal a high level of admixture of the Sucre–Anzoátegui population. The importance of specific conditions which have acted differently in the Venezuelan populations, such as founder effect, genetic drift, isolation, and endogamy are discussed. Genetic distances between the Sucre–Anzoátegui sample and several other human populations calculated on the basis of the HBB*S and HBB*A haplotypes revealed similar results, the closest genetic relationships being observed in relation to Bantu‐speaking groups. These results confirm the utility of the β‐globin haplotypes for population studies and contribute to knowledge of the Venezuelan gene pool. Am. J. Hum. Biol. 15:29–37, 2003. © 2002 Wiley‐Liss, Inc.     

Lay perceptions of genetic risks attributable to inbreeding in pakistan

Pakistan along with many other West and South Asian countries has a very high prevalence of consanguineous, especially close cousin, marriages. Although there is substantial empirical information on offspring morbidity and mortality attributable to parental consanguinity, population‐based information on how communities in general, and women in particular, perceive the health risks associated with consanguineous unions is limited. This paper considers community perceptions of health effects associated with consanguineous marriages using qualitative data from 15 focus group discussions and 294 in‐depth interviews. The study was conducted in four low‐income, multi‐ethnic, and multi‐religious communities in Karachi, the principal commercial center of Pakistan. The results show a general lack of awareness of the possible adverse health effects of consanguineous marriage. In cases where a link between consanguinity and ill health was acknowledged, it often centered on the familial origins of non‐communicable disorders such as diabetes and hypertension or infectious diseases such as tuberculosis. Belief in fate and the “evil eye” was widespread across all ethnic and religious groups. Many respondents did not agree with medical explanations of a genetic mode of disease inheritance, even in cases where there was an affected child in the family. The absence of a uniform manifestation of disease among all children of a couple who were identified as carriers of a specific mutation added to the confusion among participants. The study highlights the need for further quantification of risks associated with consanguinity and a need for provision of appropriate information to primary‐care clinicians and also to communities. The likely impact of increasing morbidity attributable to inbreeding on the health care system in resource poor settings is also discussed. Am. J. Hum. Biol. 14:264–274, 2002. © 2002 Wiley‐Liss, Inc.     

Molecular epidemiology of hepatitis B virus in Afro-Venezuelan populations

Summary.  Hepatitis B virus (HBV) infection among Venezuelan populations of African origin was analyzed. These populations exhibited lower HBV prevalence than the one found in the African continent. Sequence analysis of 6 isolates showed that 3 belonged to genotype F, while the 3 others were HBV genotype A. HBV genotype A was more common in the Afro-Venezuelan groups than in the general Venezuelan population. This might reflect the introduction of genotype A during the slavery period. The absence of the African genotype E among these isolates supports the hypothesis of a recent origin for this HBV genotype. HBV genotype F has already been introduced to these relatively isolated communities. Received February 18, 2002; accepted March 8, 2002 Published online July 22, 2002     

Genetic origins in a South American clefting population

It has been proposed that susceptibility to clefting in South America is related to Amerindian ancestry, where clefting is present at a higher frequency than in the other admixed populations (Caucasian and African) that make up the diverse racial mix of current South Americans. To clarify the genetic origins and establish a method for genetic mapping, mitochondrial DNA variation and Y-chromosome markers were studied in a South American population affected with clefting. Two-hundred and seventeen subjects and matched controls were selected through the Latin-American Collaborative Study of Congenital Malformations (ECLAMC). The case group showed a higher frequency of Native American haplogroups and a lower frequency of African haplogroups (p < 0.00001). In addition, the case group showed a much higher frequency of the specific native American haplogroup D than the control group (p < 0.00001). For the Y-chromosome markers, the case group showed a lower frequency of the African-specific marker, YAP (p = 0.002), and a higher frequency of the Native American-specific marker, DYS199 (p < 0.00001). Even though differences were found in the frequencies of the markers studied, the contribution of each founder population was similar for both groups. Results suggest a strong Native American maternal contribution and a strong Caucasian (Spanish and Portuguese) paternal contribution to the population studied. The implications of this finding include the possibility of using admixture mapping approaches to this population.     

Subgenotype diversity of hepatitis B virus American genotype F in Amerindians from Venezuela and the general population of Colombia

The objective of this study was the evaluation of the genetic diversity found in HBV circulating among Venezuelan Amerindians and the general population in Colombia. Phylogenetic analysis of the S region in 194 isolates showed that genotype F is highly predominant in Colombia and Venezuela. This might be related to the genetic background of the population. F3 is the main subgenotype which circulates in both countries. Phylogenetic analysis of 61 complete genome sequences of HBV American genotypes confirms the presence of two genotypes F and H, and 4 F subgenotypes. In Venezuela, subgenotypes F1, F2, and F3 circulate in East and West Amerindians, while only F3 was found among South Amerindians. Japreira community derived from Yucpa Amerindians around 150 years ago. However, several Japreira HBV sequences were forming a clade that can be classified as subgenotype 2b, differing from Yucpa sequences that belong mainly to subgenotype F3. The apparent absence of correlation between the phylogenetic groupings of HBV isolates with the ethnical origin in aboriginal populations might be suggesting a recent origin of HBV American subgenotypes, or a genetic drift effect.     

Mitochondrial DNA diversity in the Llanos de Moxos: Moxo, Movima and Yuracare Amerindian populations from Bolivia lowlands

BACKGROUND: Movima, Yuracare, Ignaciano and Trinitario are Amerindian populations living in the Bolivian lowlands of the Amazonian basin. The cultural and genetic affinity of the peoples living in this area is poorly known, despite many archaeological studies demonstrating its importance in pre-Columbian times. Densely populated Amerindian groups occupied the region, both in the Llanos and along the river streams of the Amazonian basin, practising intense agricultural activities and exchange of goods. The historical and linguistic records indicate that the land was occupied through successive migrations that gave rise to complex socio-economic communities. Genetic information suggests that the colonization of the American continent was fairly simple from a emigrational point of view, but other evolutionary processes, such as genetic drift or natural selection, could have also shaped the genetic background of present day populations in the Beni region. AIM: The objective of this study is to characterize the genetic diversity of these populations by analysing the sequence variability of the HVR-I control region in the mitochondrial DNA (mtDNA). The Amerindian origin of these populations suggests that close genetic similarities should be evident between the Beni samples studied here and other Amerindian groups. However, complex processes of population interactions and/or isolation in the Beni region might result in non-expected genetic affinities. SUBJECTS AND METHODS: DNA was extracted from pulled-out hairs obtained in situ from non-closely related individuals living in the Beni Department in Bolivia. DNA was extracted using a standard Chelex 100 method and a 401 bp DNA fragment of the HVR-I region was amplified using specific primers (L-15978 and H-16412). DNA amplicons were purified by centrifugation using Microspin S-300 HR columns and both SNA strands were sequenced after asymmetric PCR using direct Dye-Terminator 2 sequencing kit (Perkin-Elmer). Two independent 401 and 328 bp DNA fragments were sequenced separately for each sample. The sequence analyses includes mismatch distributions and mean pairwise differences, median network analysis, and neighbour joining, maximum likelihood phylogenetic comparisons. Genetic diversity of DNA sequences was also measured in various ways for the sample studied and UPGMA trees were drawn, including a large number of South Amerindian sequences. RESULTS: The genetic diversity of 401 nucleotide long mtDNA sequences in the hypervariable control region, from positions 16,000-16,400, was characterized in a sample of 54 Amerindians living in the Llanos de Moxos. A total of 34 distinct lineages were observed, defined by 41 variable nucleotide positions, and 70.6% of all lineages were single sequences. All four major Amerindian haplogroups were detected (A 18.5%, n=10; B 24.1%, n=13, C 50.0% n=27; and D 5.6%, n=3). The median network analysis observed suggests that processes of population expansion took place in the Beni region. However, no clear haplotype differentiation by population could be detected. High levels of molecular variability and a bimodal pair-wise mismatch distribution were seen within the sample. The analyses of molecular variance (AMOVA) showed that most of the variance observed was due to intrapopulation variability, and that the highest among-groups variance was obtained when a linguistic classification criteria was used. The phylogenetic comparison revealed unique lineages in the Beni areas, not reported for other Amerindian populations. CONCLUSIONS: The genetic diversity observed in the Beni area is higher than that observed in other American populations living in much larger areas and with a long, known evolutionary history, despite the reduced area of Moxos. This could result from processes of reproductive isolation between groups, followed by population expansions and migration, where genetic drift might have be a major evolutionary force in population differentiation.     

Distribution of CGG repeats and FRAXAC1/DXS548 alleles in South American populations

In order to assess the molecular variability related to fragile X (FMR1 locus), we investigated the distribution of CGG repeats and DXS548/FRAXAC1 haplotypes in normal South American populations of different ethnic backgrounds. Special attention was given to Amerindian Wai-Wai (Northern Brazil) and Ache (Paraguay), as well as to Brazilian isolated communities of African ancestry, the remnants of quilombos. Comparison of samples from quilombos, Amerindians, and the ethnically mixed, but mainly European-derived population of S?o Paulo revealed that the 30-copy allele of the fragile X gene is the most frequent in all groups. A second peak at 20 repeats was present in the population of S?o Paulo only, confirming this as a European peculiarity. The distribution of DXS548 and FRAXAC1 alleles led to a high expected heterozygosity in African Brazilians, followed by that observed in the population of S?o Paulo. Amerindians showed the lowest diversity in CGG repeats and DXS548/FRAXAC1 haplotypes. Some rare alleles, for example, the 148-bp (FRAXAC1) or 200-bp (DXS548) variants, which seem to be almost absent in Europe, occurred in higher frequencies among African Brazilians. This suggests a general trend for higher genetic diversity among Africans; these rarer alleles could be African in origin and would have been lost or possibly were not present in the groups that gave rise to the Europeans.     

Mitochondrial DNA diversity in the Llanos de Moxos: Moxo,Movima and Yuracare Amerindian populations from Bolivia lowlands

Background: Movima, Yuracare, Ignaciano and Trinitario are Amerindian populations living in the Bolivian lowlands of the Amazonian basin. The cultural and genetic affinity of the peoples living in this area is poorly known, despite many archaeological studies demonstrating its importance in pre-Columbian times. Densely populated Amerindian groups occupied the region, both in the Llanos and along the river streams of the Amazonian basin, practising intense agricultural activities and exchange of goods. The historical and linguistic records indicate that the land was occupied through successive migrations that gave rise to complex socio-economic communities. Genetic information suggests that the colonization of the American continent was fairly simple from a emigrational point of view, but other evolutionary processes, such as genetic drift or natural selection, could have also shaped the genetic background of present day populations in the Beni region.

Aim: The objective of this study is to characterize the genetic diversity of these populations by analysing the sequence variability of the HVR-I control region in the mitochondrial DNA (mtDNA). The Amerindian origin of these populations suggests that close genetic similarities should be evident between the Beni samples studied here and other Amerindian groups. However, complex processes of population interactions and/or isolation in the Beni region might result in non-expected genetic affinities.

Subjects and methods: DNA was extracted from pulled-out hairs obtained in situ from non-closely related individuals living in the Beni Department in Bolivia. DNA was extracted using a standard Chelex? 100 method and a 401?bp DNA fragment of the HVR-I region was amplified using specific primers (L-15978 and H-16412). DNA amplicons were purified by centrifugation using Microspin? S-300 HR columns and both SNA strands were sequenced after asymmetric PCR using direct Dye-Terminator 2 sequencing kit (Perkin-Elmer). Two independent 401 and 328?bp DNA fragments were sequenced separately for each sample. The sequence analyses includes mismatch distributions and mean pairwise differences, median network analysis, and neighbour joining, maximum likelihood phylogenetic comparisons. Genetic diversity of DNA sequences was also measured in various ways for the sample studied and UPGMA trees were drawn, including a large number of South Amerindian sequences.

Results: The genetic diversity of 401 nucleotide long mtDNA sequences in the hypervariable control region, from positions 16?000–16?400, was characterized in a sample of 54 Amerindians living in the Llanos de Moxos. A total of 34 distinct lineages were observed, defined by 41 variable nucleotide positions, and 70.6% of all lineages were single sequences. All four major Amerindian haplogroups were detected (A 18.5%, n=10 ; B 24.1%, n=13, C 50.0% n=27 ; and D 5.6%, n=3). The median network analysis observed suggests that processes of population expansion took place in the Beni region. However, no clear haplotype differentiation by population could be detected. High levels of molecular variability and a bimodal pair-wise mismatch distribution were seen within the sample. The analyses of molecular variance (AMOVA) showed that most of the variance observed was due to intrapopulation variability, and that the highest among-groups variance was obtained when a linguistic classification criteria was used. The phylogenetic comparison revealed unique lineages in the Beni areas, not reported for other Amerindian populations.

Conclusions: The genetic diversity observed in the Beni area is higher than that observed in other American populations living in much larger areas and with a long, known evolutionary history, despite the reduced area of Moxos. This could result from processes of reproductive isolation between groups, followed by population expansions and migration, where genetic drift might have be a major evolutionary force in population differentiation.     

New genetic data on Amerindians from the Paraguayan Chaco

New data on 17 blood group and protein genetic systems obtained among the Ayoreo and Lengua Indians of Paraguay are presented. They include the first report on the red cell band‐3 protein investigated among South American Indians. This information was integrated with previous results available for these two and four other groups. Five of the six populations reside in the Chaco area, while the sixth was included as an outgroup living elsewhere in Paraguay. Four of the five Chaco tribes exhibit good genetic homogeneity, but the Ayoreo are somewhat different. The results confirm the Chaco as a distinct biological (as well as cultural and economic) region, which should be considered in evaluations of genetic variability among South American Indians. Am. J. Hum. Biol. 13:660–667, 2001. © 2001 Wiley‐Liss, Inc.     

Y-chromosome haplogroup diversity in the sub-Himalayan Terai and Duars populations of East India

The sub-Himalayan Terai and Duars, the important outermost zones comprising the plains of East India, are known as the reservoirs of ethnic diversity. Analysis of the paternal genetic diversity of the populations inhabiting these regions and their genetic relationships with adjacent Himalayan and other Asian populations has not been addressed empirically. In the present investigation, we undertook a Y-chromosome phylogeographic study on 10 populations (n=375) representing four different linguistic groups from the sub-Himalayan Terai and Duars regions of East India. The high-resolution analysis of Y-chromosome haplogroup variations based on 76 binary markers revealed that the sub-Himalayan paternal gene pool is extremely heterogeneous. Three major haplogroups, namely H, O and R, are shared across the four linguistic groups. The Indo-European-speaking castes exhibit more haplogroup diversity than the tribal groups. The findings of the present investigation suggest that the sub-Himalayan gene pools have received predominant Southeast Asian contribution. In addition, the presence of Northeast and South Asian signatures illustrate multiple events of population migrations as well as extensive genetic admixture amongst the linguistic groups.     

Admixture estimates for Churuguara, a Venezuelan town in the State of Falcón

BACKGROUND: The present Venezuelan population is the admixture product of Amerindians, Europeans and Africans, a process which was not homogeneous over the country. Blood groups, STRs and VNTRs, specifically D1S80, have been used successfully in admixture studies, but few have been made in Venezuela. AIM: This study aims to estimate the admixture components of Churuguara, Venezuela, and to evaluate the genetic relationship of this population with other Venezuelan as well as worldwide populations through principal component analysis and the study of dendrograms based on genetic distances. SUBJECTS AND METHODS: Gene frequencies of blood groups ABO and Rh (only anti D), of STRs VWA, F13A01, FES/FPS and VNTR D1S80 were studied in a sample of 60 individuals born in Churuguara, a Venezuelan town of admixed ancestry in the State of Falc6n. Admixture was estimated with Chakraborty's gene identity method, and Nei's standard genetic distance was used to build two dendrograms with the neighbour-joining approach, one based on the three STRs and the other based only on D1S80. Principal component analyses with the gene frequencies of these markers were also performed. RESULTS: The frequency of allele ABO*O was 0.788, of ABO*A was 0.187 and of RH*D was 0.74. D1S80 showed 16 different alleles with a heterozygosity of 0.880, whilst the three STRs showed only eight different alleles and heterozygosities between 0.733 and 0.797. The estimates of admixture obtained in this analysis were 52.5% for the Spanish parental group, 27.6% for the African and 19.9% for the Amerindian. Comparison of Churuguara with other Latin American populations shows that its African component is not as high as that observed in Colombian Choco, but it is higher than that observed in other samples from Colombia, Chile and Maracaibo (Venezuela). CONCLUSIONS: Results of the admixture analysis are consistent with those obtained with two dendrograms and principal component analyses, suggesting that the strong initial Amerindian component of 500 years ago has been diluted by the continuous flow of European genes, mainly Spanish, to this region.     

Genetic admixture in three mexican mestizo populations based on D1S80 and HLA‐DQA1 Loci

This study compares genetic polymorphisms at the D1S80 and HLA‐DQA1 loci in three Mexican Mestizo populations from three large states (Nuevo León, Jalisco, and the Federal District). Allele frequency distributions are relatively homogenous in the three samples; only the Federal District population shows minor differences of the HLA‐DQA1 allele frequencies compared with the other two. In terms of genetic composition, these Mestizo populations show evidence of admixture with predominantly Spanish‐European (50–60%) and Amerindian (37–49%) contributions; the African contribution (1–3%) is minor. Together with the observation that in Nuevo León, the admixture estimates based on D1S80 and HLA‐DQA1, are virtually the same as those reported earlier from blood group loci, suggests that DNA markers, such as D1S80 and HLA‐DQA1 are useful for examining genetic homogeneity/heterogeneity across Mestizo populations of Mexico. The inverse relationship of the proportion of gene diversity due to population differences (G_st) to within population gene diversity (H_s) is also consistent with theoretical predictions, supporting the use of these markers for population genetics studies. Am. J. Hum. Biol. 14:257–263, 2002. © 2002 Wiley‐Liss, Inc.     

Hispano-Indian admixture in Paraguay studied by analysis of HLA-DRB1 polymorphism

The genetic polymorphism of the Paraguayan population results from the admixture between South American Indians named Guaranis and Spaniards. In order to evaluate the genetic predominance in the Paraguayan population, we typed 50 healthy Paraguayans for HLA-DRB1 by molecular biology and compared their HLA-DRB1 polymorphism to that of the Guaranis and of two Spanish populations. Six significant differences of alleles frequencies were observed between Paraguayans and Guaranis--DRB1*01, 06 (13, 14), 15, 16, 07--whereas only one difference was observed with the Spaniards (DRB1*14). The DRB1*14 frequency was higher in Paraguayan than in the Spanish populations essentially due to the presence of DRB1*1402 related alleles (1402,06,13). These alleles are extremely rare in the Spanish populations whereas frequent in the Guaranis from Brazil and in South American Indian tribes living in the lymitrophe regions of Paraguay (Toba, Wichi and Terena). Thus, the presence of the DRB1*1402 related alleles (6%) in the Paraguayan population constitutes the major Indian contribution to the HLA-DR polymorphism of the Paraguayan population. The genetic distances between Paraguayans and the two Spanish populations were closer (.494 and .415) than that between Paraguayans and Guaranis (.958). Altogether these results suggest the predominance of the Spanish genetic in the Paraguayan population. Historical events are discussed to explain this predominance.     

Transmission of Venezuelan equine encephalomyelitis virus by strains of Aedes albopictus (Diptera: Culicidae) collected in North and South America

Experimental studies were undertaken to ascertain the vector potential of North American (Houston and Alsace) and South American (Sao Paulo and Santa Teresa) strains of Aedes albopictus (Skuse) for an epizootic (Trinidad donkey) strain of Venezuelan equine encephalomyelitis (VEE) virus. Infection rates were similar in all four strains of Ae. albopictus tested after ingestion of VEE virus from a viremic hamster. Virus disseminated from the midgut to the hemocoel in about 80% of infected mosquitoes, regardless of the dose ingested (10(4.6) to 10(5.7) plaque-forming units per mosquito) or the time of extrinsic incubation (7-35 d). Although all four strains of this mosquito transmitted VEE virus by bite to hamsters, transmission rates were significantly higher for the South American strains (24%, 40 of 170) than for the North American strains (5%, 9 of 165). Although VEE virus has never been isolated from Ae. albopictus, the introduction of this species into the Americas may allow it to serve as an amplification vector in areas where epizootic strains of VEE are found or introduced.     

New data on the genetic structure of the population of Sicily: Analysis of the Alia population (Palermo,Italy)

The distribution of 13 genetic markers (AB0, Rh, ACP, ADA, AK, ESD, GLO, PGD, PGMl, SOD, GC, TF, and PI) were studied in a sample from the Alia population of Sicily, Italy. A total of 34 alleles were detected. In comparison with other Sicilian populations, Alia always appeared genetically distinctive, either in terms of overall genetic diversity or for the number of unique alleles present. The results are consistent with previous studies that show no genetic uniformity within the island. More specifically, the data support the genetic divergence of the eastern and western halves of the island and highlight genetic boundaries that run through Sicily and divide it into three distinct areas. Am. J. Hum. Biol. 14:289–299, 2002. © 2002 Wiley‐Liss, Inc.     

Extended HLA haplotypes among the Bari Amerindians of the Perija Range : Relationship to other tribes based on four-loci haplotype frequencies

Extended HLA haplotypes among Bari Amerindians living at the Perija Range on the limits between Colombia and Venezuela have been defined using serology for class I, electrophoresis and immuno-fixation for Bf and C4, and PCR-SSO for class II loci typing. Haplotypes were assigned based on family studies and gene frequencies were calculated using a subset of less related subjects selected from the genealogy. No rare class III variants were observed, but the characteristic low HLA diversity of isolated Amerindian populations present also in the Bari extends to Bf and C4. Thus there were only 22 different haplotypes segregating in families when nine loci were considered. All of them except three carried Bf^*S, C4A^*3, C4B^*1. The null allele C4A^*Q0 reached a frequency of 0.147 and was predominantly present in A24 Cw7 B39 DRB1^*0411 haplotypes. In contrast to what has been reported using HLA alleles or class I haplotype frequencies and other isolated South American tribes, genetic distance estimates based on A-Cw-B-DR haplotype frequencies show a closer relationship between the two linguistically but geographically distant Venezuelan tribes, the Bari and the Warao, as compared to two culturally different Brazilian populations. The information reported here will be useful for identifying ancestral haplotypes in native peoples of America, for population comparison, and for discussing the differential influence of MHC haplotype diversity and population survival when similar data on other Amerindian tribes becomes available.     

Phylogeny of the Venezuelan arenaviruses

Guanarito virus (the etiologic agent of Venezuelan hemorrhagic fever, VHF) and Pirital virus coexist in the region of Venezuela in which Venezuelan hemorrhagic fever is endemic. The purpose of this study was to extend our knowledge of the evolutionary relationship between these two arenaviruses. We determined that the large genomic segments of Guanarito virus and Pirital virus are similar in size and identical in structural organization to the large genomic segments of other South American arenaviruses. For example, the Z proteins and RNA-dependent RNA polymerases of Guanarito virus and Pirital virus are encoded in nonoverlapping open reading frames of opposite polarities. Phylogenetic analyses of Z protein gene nucleotide sequences and RNA-dependent RNA polymerase gene nucleotide sequences grouped Pirital virus with Pichindé virus (a South American arenavirus which, like Pirital virus, does not appear to be pathogenic for humans) and placed the Pirital-Pichindé lineage in a sister relationship to a lineage represented by Guanarito virus and the three other arenaviruses known to cause hemorrhagic fever in South America. These results are concordant with the results of studies on the phylogeny of the arenavirus small genomic segment. Thus, the exchange of genomic elements between Guanarito virus and Pirital virus via recombination or reassortment likely did not contribute to the emergence of Venezuelan hemorrhagic fever.     

Diversity and Divergence Among the Tribal Populations of India

Tribal populations of the Indian subcontinent have been of longstanding interest to anthropologists and human geneticists. To investigate the relationship of Indian tribes to Indian castes and continental populations, we analyzed 45 unlinked autosomal STR loci in 9 tribal groups, 8 castes, and 18 populations from Africa, Europe and East Asia. South Indian tribal populations demonstrate low within‐population heterozygosity (range: 0.54 – 0.69), while tribal populations sampled further north and east have higher heterozygosity (range: 0.69 – 0.74). Genetic distance estimates show that tribal Indians are more closely related to caste Indians than to other major groups. Between‐tribe differentiation is high and exceeds that for eight sub‐Saharan African populations (4.8% vs. 3.7%). Telugu‐speaking populations are less differentiated than non‐Telugu speakers (F_ST: 0.029 vs. 0.079), but geographic distance was not predictive of genetic affinity between tribes. South Indian tribes show significant population structure, and individuals can be clustered statistically into groups that correspond with their tribal affiliation. These results are consistent with high levels of genetic drift and isolation in Indian tribal populations, particularly those of South India, and they imply that these populations may be potential candidates for linkage disequilibrium and association mapping.     

Dissimilarities in the process of formation of curiaú, a semi‐isolated Afro‐Brazilian population of the Amazon region

The genetic consequences of the social policy of the past in relation to the formation of Afro‐Brazilian societies are interesting and have been studied at various biological levels (classical polymorphisms and the mitochondrial and nuclear levels. These allow the estimation of the contribution of African genes and the participation of other ethnic groups in the formation of these communities. With this objective, uniparental systems of exclusively maternal (mtDNA) or paternal (Y‐DNA) inheritance in the Curiaú community were analyzed. The results demonstrate a differential contribution of the maternal and paternal genetic systems. Thirty‐three sequences were identified by mtDNA analysis; 53% showing an African and 47% an Amerindian origin. For the paternal system, 57% were of African, 37% of European, and 6% of Amerindian origin. Am. J. Hum. Biol. 14:440–447, 2002. © 2002 Wiley‐Liss, Inc.