Differential distribution of NAT2 polymorphisms and NAT2 acetylator phenotypes among indigenous populations of the Brazilian Amazon.

OBJECTIVES: We report, for the first time, the distribution of four no-function NAT2 single nucleotide polymorphisms and inferred NAT2 acetylator phenotypes in three indigenous groups (Munduruku, Paiter-Suruí, and Yanomami), living in reservation areas in the Brazilian Amazon. METHODS: Two hundred and seventy-six participants from three indigenous groups (92 for each group) were included and genotyped for four NAT2 polymorphisms (rs1801279, rs1801280, rs1799930, and rs1799931) by the TaqMan system. Minor Allele Frequency (MAF) was determined and NAT2 acetylator phenotypes were inferred. RESULTS: NAT2 rs1801279G>A was absent in all cohorts; rs1799930G>A was absent in Yanomami and rare (MAF 0.016) in Munduruku and Paiter-Suruí; MAF of rs1801280T>C ranged five-fold (0.092-0.433), and MAF of rs1799931G>A varied between 0.179 and 0.283, among the three groups. The distribution of NAT2 phenotypes differed significantly across cohorts; the prevalence of the slow acetylator phenotype ranged from 16.3% in Yanomami to 33.3% in Munduruku to 48.9% in Paiter-Suruí. This three-fold range of variation is of major clinical relevance because the NAT2 slow phenotype is associated with higher risk of hepatotoxicity with antituberculosis chemotherapy and high incidence rates of tuberculosis and burden of latent infection among Munduruku, Paiter-Surui, and Yanomami peoples. According to the frequency of the NAT2 slow acetylator phenotype, the estimated number of individuals needed to be genotyped to prevent one additional event of hepatotoxicity range from 31 (Munduruku) to 39 (Paiter-Surui) and to 67 (Yanomami). CONCLUSION: The rs1801279 polymorphism was not found in any of the cohorts, while the MAF of the other polymorphisms showed significant variation between the cohorts. The difference in the prevalence of the NAT2 slow acetylator phenotype, which is linked to isoniazid-induced hepatotoxicity, was observed in the different study cohorts.

Genomic surveillance of malaria parasites in an indigenous community in the Peruvian Amazon.

Hard-to-reach communities represent Peru's main challenge for malaria elimination, but information about transmission in these areas is scarce. Here, we assessed Plasmodium vivax (Pv) and P. falciparum (Pf) transmission dynamics, resistance markers, and Pf hrp2/3 deletions in Nueva Jerusalén (NJ), a remote, indigenous community in the Peruvian Amazon with high population mobility. We collected samples from November 2019 to May 2020 by active (ACD) and passive case detection (PCD) in NJ. Parasites were identified with microscopy and PCR. Then, we analyzed a representative set of positive-PCR samples (Pv = 68, Pf = 58) using highly-multiplexed deep sequencing assays (AmpliSeq) and compared NJ parasites with ones from other remote Peruvian areas using population genetics indexes. The ACD intervention did not reduce malaria cases in the short term, and persistent malaria transmission was observed (at least one Pv infection was detected in 96% of the study days). In Nueva Jerusalen, the Pv population had modest genetic diversity (He = 0.27). Pf population had lower diversity (He = 0.08) and presented temporal clustering, one of these clusters linked to an outbreak in February 2020. Moreover, Pv and Pf parasites from NJ exhibited variable levels of differentiation (Pv Fst = 0.07-0.52 and Pf Fst = 0.11-0.58) with parasites from other remote areas. No artemisin resistance mutations but chloroquine (57%) and sulfadoxine-pyrimethamine (35-67%) were detected in NJ's Pf parasites. Moreover, pfhrp2/3 gene deletions were common (32-50% of parasites with one or both genes deleted). The persistent Pv transmission and the detection of a Pf outbreak with parasites genetically distinct from the local ones highlight the need for tailored interventions focusing on mobility patterns and imported infections in remote areas to eliminate malaria in the Peruvian Amazon.

Detection through the use of RT-MqPCR of asymptomatic reservoirs of malaria in samples of patients from the indigenous Comarca of Guna Yala, Panama: Essential method to achieve the elimination of malaria.

BACKGROUND: Plasmodium vivax is the main causative agent of malaria in Panama. However, the prevalence of asymptomatic infections in the different endemic regions remains unknown. Understanding the epidemiological behavior of asymptomatic infections is essential for the elimination of malaria. This study aimed to determine the prevalence of asymptomatic malarial infections in one of the main endemic regions of Panama using multiplex real-time reverse transcription RT-MqPCR. METHODS: A cross-sectional study was conducted in three communities in the Guna Yala Comarca. A total of 551 thick blood smears and their respective samples on filter paper were collected from volunteers of different ages and sexes from June 20 to 25, 2016. Infections by the Plasmodium spp. were diagnosed using microscopy and RT-MqPCR. All statistical analyses were performed using the R software. RESULTS: The average prevalence of asymptomatic infections by P. vivax in the three communities detected by RT-MqPCR was 9.3%, with Ukupa having the highest prevalence (13.4%), followed by Aidirgandi (11.1%) and Irgandi (3.3%). A total of 74 samples were diagnosed as asymptomatic infections using RT-MqPCR. Light microscopy (LM) detected that 17.6% (13/74) of the asymptomatic samples and 82.4% (61/74) were diagnosed as false negatives. A 100% correlation was observed between samples diagnosed using LM and RT-MqPCR. A total of 52.7% (39/74) of the asymptomatic patients were female and 85.1% (63/74) were registered between the ages of 1 and 21 years. Factors associated with asymptomatic infection were community (aOR = 0.38 (95% CI 0.17-0.83), p < 0.001) and age aOR = 0.98 (95% CI 0.97-1.00), p < 0.05); F = 5.38; p < 0.05). CONCLUSIONS: This study provides novel evidence of the considerable prevalence of asymptomatic P. vivax infections in the endemic region of Kuna Yala, representing a new challenge that requires immediate attention from the National Malaria Program. The results of this study provide essential information for the health authorities responsible for developing new policies. Furthermore, it will allow program administrators to reorient and design effective malaria control strategies that consider asymptomatic infections as a fundamental part of malaria control and move towards fulfilling their commitment to eliminate it.

Molecular Profile of Variants Potentially Associated with Severe Forms of COVID-19 in Amazonian Indigenous Populations.

Coronavirus disease 2019 (COVID-19) is an infection caused by SARS-CoV-2. Genome-wide association studies (GWASs) have suggested a strong association of genetic factors with the severity of the disease. However, many of these studies have been completed in European populations, and little is known about the genetic variability of indigenous peoples' underlying infection by SARS-CoV-2. The objective of the study is to investigate genetic variants present in the genes AQP3, ARHGAP27, ELF5L, IFNAR2, LIMD1, OAS1 and UPK1A, selected due to their association with the severity of COVID-19, in a sample of indigenous people from the Brazilian Amazon in order to describe potential new and already studied variants. We performed the complete sequencing of the exome of 64 healthy indigenous people from the Brazilian Amazon. The allele frequency data of the population were compared with data from other continental populations. A total of 66 variants present in the seven genes studied were identified, including a variant with a high impact on the ARHGAP27 gene (rs201721078) and three new variants located in the Amazon Indigenous populations (INDG) present in the AQP3, IFNAR2 and LIMD1 genes, with low, moderate and modifier impact, respectively.

Genetic continuity and change among the Indigenous peoples of California.

Before the colonial period, California harboured more language variation than all of Europe, and linguistic and archaeological analyses have led to many hypotheses to explain this diversity1. We report genome-wide data from 79 ancient individuals from California and 40 ancient individuals from Northern Mexico dating to 7,400-200 years before present (BP). Our analyses document long-term genetic continuity between people living on the Northern Channel Islands of California and the adjacent Santa Barbara mainland coast from 7,400 years BP to modern Chumash groups represented by individuals who lived around 200 years BP. The distinctive genetic lineages that characterize present-day and ancient people from Northwest Mexico increased in frequency in Southern and Central California by 5,200 years BP, providing evidence for northward migrations that are candidates for spreading Uto-Aztecan languages before the dispersal of maize agriculture from Mexico2-4. Individuals from Baja California share more alleles with the earliest individual from Central California in the dataset than with later individuals from Central California, potentially reflecting an earlier linguistic substrate, whose impact on local ancestry was diluted by later migrations from inland regions1,5. After 1,600 years BP, ancient individuals from the Channel Islands lived in communities with effective sizes similar to those in pre-agricultural Caribbean and Patagonia, and smaller than those on the California mainland and in sampled regions of Mexico.

Human genetics: Rich genomic history of two isolated Indigenous peoples of South America.

Genome-wide data from two Indigenous South American groups reveal their dynamic population history. The Mapuche from Southern Chile and the Ashaninka from Amazonian Peru remained largely isolated over time. Yet, both groups interacted with other South American peoples sporadically.

Epidemiological-molecular profile of variants associated with type 2 diabetes mellitus in indigenous populations from the Brazilian Amazon.

AIMS: While lifestyle factors are strongly associated with Type 2 diabetes (T2DM), genetic characteristics also play a role. However, much of the research on T2DM genetics focuses on European and Asian populations, leaving underrepresented groups, such as indigenous populations with high diabetes prevalence, understudied. METHODS: We characterized the molecular profile of 10 genes involved in T2DM risk through complete exome sequencing of 64 indigenous individuals belonging to 12 different Amazonian ethnic groups. RESULTS: The analysis revealed 157 variants, including four exclusive variants in the indigenous population located in the NOTCH2 and WFS1 genes with a modifier or moderate impact on protein effectiveness. Furthermore, a high impact variant in NOTCH2 was also found. Additionally, the frequency of 10 variants in the indigenous group showed significant differences when compared to other global populations that were evaluated. CONCLUSION: Our study identified 4 novel variants associated with T2DM in the NOTCH2 and WFS1 genes in the Amazonian indigenous populations we studied. In addition, a variant with a high predicted impact in NOTCH2 was also observed. These findings represent a valuable starting point for conducting further association and functional studies, which could help to improve our understanding of the unique characteristics of this population.

Methylation patterns of the CDKN2B and CDKN2A genes in an indigenous population exposed to pesticides.

The INK4-ARF locus includes the CDKN2B and CDKN2A genes and is functionally relevant in the regulation of both cell proliferation and senescence. Studies have reported modifications of DNA methylation in this locus by exposure to environmental contaminants including pesticides; however, until now, specific methylation profiles have not been reported in genetically conserved populations exposed to occupational pesticides. The aim of this study was to determine the methylation profiles of the CDKN2B and CDKN2A genes in a genetically conserved population exposed to pesticides. A cross-sectional and analytical study was carried out in 190 Huichol indigenous persons. Information related to pesticide exposure, diet and other variables were obtained through the use of a structured questionnaire. Blood and urine samples were collected for methylation test and dialkylphosphates (DAP) determination, respectively. DNA methylation was measured by the pyrosequencing of bisulfite-treated DNA and DAP concentrations by gas chromatography-tandem mass spectrometry (GC/MS). The most frequent metabolite in the population was dimethylthiophosphate. The farmer group presented a higher methylation percentage of CDKN2B than the non-farmer group, but no differences in CDKN2A were observed between groups. A positive correlation between methylation of CpG site 3 of CDKN2B and time working in the field was observed in the farmer group. An association between methylation percentage of CDKN2B and age was also observed in the non-farmer group. These results suggest that pesticide exposure and exposure time in Huichol indigenous individuals could modify the methylation pattern of the CDKN2B gene.

Weaving Mitochondrial DNA and Y-Chromosome Variation in the Panamanian Genetic Canvas.

The Isthmus of Panama was a crossroads between North and South America during the continent's first peopling (and subsequent movements) also playing a pivotal role during European colonization and the African slave trade. Previous analyses of uniparental systems revealed significant sex biases in the genetic history of Panamanians, as testified by the high proportions of Indigenous and sub-Saharan mitochondrial DNAs (mtDNAs) and by the prevalence of Western European/northern African Y chromosomes. Those studies were conducted on the general population without considering any self-reported ethnic affiliations. Here, we compared the mtDNA and Y-chromosome lineages of a new sample collection from 431 individuals (301 males and 130 females) belonging to either the general population, mixed groups, or one of five Indigenous groups currently living in Panama. We found different proportions of paternal and maternal lineages in the Indigenous groups testifying to pre-contact demographic events and genetic inputs (some dated to Pleistocene times) that created genetic structure. Then, while the local mitochondrial gene pool was marginally involved in post-contact admixtures, the Indigenous Y chromosomes were differentially replaced, mostly by lineages of western Eurasian origin. Finally, our new estimates of the sub-Saharan contribution, on a more accurately defined general population, reduce an apparent divergence between genetic and historical data.

Uniparental Lineages from the Oldest Indigenous Population of Ecuador: The Tsachilas.

Together with Cayapas, the Tsachilas constitute the oldest population in the country of Ecuador and, according to some historians, they are the last descendants of the ancient Yumbos. Several anthropological issues underlie the interest towards this peculiar population: the uncertainty of their origin, their belonging to the Barbacoan linguistic family, which is still at the center of an intense linguistic debate, and the relations of their Yumbo ancestors with the Inca invaders who occupied their ancient territory. Our contribution to the knowledge of their complex past was the reconstruction of their genetic maternal and paternal inheritance through the sequencing of 70 entire mitochondrial genomes and the characterization of the non-recombinant region of the Y chromosome in 26 males. For both markers, we built comprehensive datasets of various populations from the surrounding geographical area, northwestern South America, NW, with a known linguistic affiliation, and we could then compare our sample against the overall variability to infer relationships with other Barbacoan people and with other NW natives. We found contrasting patterns of genetic diversity for the two markers, but generally, our results indicated a possible common origin between the Tsachilas, the Chachi, and other Ecuadorian and Colombian Barbacoans and are suggestive of an interesting ancient linkage to the Inca invaders in Yumbo country.

Deep genetic affinity between coastal Pacific and Amazonian natives evidenced by Australasian ancestry.

Different models have been proposed to elucidate the origins of the founding populations of America, along with the number of migratory waves and routes used by these first explorers. Settlements, both along the Pacific coast and on land, have been evidenced in genetic and archeological studies. However, the number of migratory waves and the origin of immigrants are still controversial topics. Here, we show the Australasian genetic signal is present in the Pacific coast region, indicating a more widespread signal distribution within South America and implicating an ancient contact between Pacific and Amazonian dwellers. We demonstrate that the Australasian population contribution was introduced in South America through the Pacific coastal route before the formation of the Amazonian branch, likely in the ancient coastal Pacific/Amazonian population. In addition, we detected a significant amount of interpopulation and intrapopulation variation in this genetic signal in South America. This study elucidates the genetic relationships of different ancestral components in the initial settlement of South America and proposes that the migratory route used by migrants who carried the Australasian ancestry led to the absence of this signal in the populations of Central and North America.

Study of 17 X-STRs in Native American and Mestizo populations of Central America for forensic and population purposes.

In the present work, an extensive analysis of the X-chromosomal pool of Native American and Mestizo groups of Central America (Guatemala, El Salvador, Nicaragua, and Panama) has been carried out. Allele and haplotype frequency databases, as well as other forensic parameters for these populations, are presented. The admixture analysis supports the tri-hybrid composition in terms of ancestry in the Mestizo populations, with a predominant Native American contribution (54-69%), followed by European (19-28%) and African contributions (12-19%). Pairwise FST genetic distances highlight the genetic proximity between the northernmost Central American populations, especially among admixed populations. The unique and complex nature of this area, where populations from different origins intercrossed, as well as the informativity of X-STR data, highpoint the great interest of this genetic study. Furthermore, the X-chromosome databases for Central American populations here provided will be not only useful for forensic and population purposes not only in the target countries but also in the host countries.

High frequency of the risk allele of rs4132601 and rs11978267 from the IKZF1 gene in indigenous Mexican population.

BACKGROUND: IKZF1 is a relevant gene associated with the pathogenesis of acute lymphoblastic leukemia, and the rs4132601 (T>G) and rs11978267 (A>G) polymorphisms have been associated with the development of this disease in several populations. The aim of this study was to determine the allelic and genotypic frequencies of the rs4132601 and rs11978267 polymorphisms in two indigenous Mexican groups (Cora and Huichol) and Mestizo populations from Nayarit, Mexico, and compare them with the frequencies of both polymorphisms in other populations of the world. METHODS: One hundred, 116, and 100 subjects from the Mestizo, Huichol, and Cora populations, respectively, all of them residents of the state of Nayarit, Mexico, were analyzed. The frequencies of rs4132601 and rs11978267 were determined by allelic discrimination using TaqMan assays. RESULTS: The allelic frequencies of rs4132601 were as follows: Mestizo group T = 0.74, G = 0.26; Cora T = 0.745, G = 0.255; and Huichol T = 0.47, G = 0.53. In the case of the rs11978267 polymorphism, the allelic frequencies were Mestizo A = 0.745, G = 0.255; Cora A = 0.735, G = 0.265; and Huichol A = 0.457, G = 0.543. For each population, both polymorphisms were in Hardy-Weinberg equilibrium. CONCLUSION: The Huichol population from Nayarit presented the highest frequencies of the risk allele reported to date in the whole world for both rs4132601 and rs11978267 polymorphisms.

Leptin G-2548A and Leptin Receptor Q223R Gene Polymorphisms are Differently Associated with Oxidative Process in Mexican Mestizo and Indigenous with Obesity.

Leptin levels and oxidative stress are implicated in obesity risk. Reports of association of leptin gene (LEP) and leptin receptor gene (LEPR) polymorphisms with leptin elevation are contradictory in a diverse population. Only a few studies report the linkage of obesity with biochemical markers and genetic factors. OBJECTIVE: The aim of this study was to examine whether plasma lipid peroxidation, antioxidant capability, leptin levels are associate selected LEP -2548 A/G and LEPR Q223R polymorphisms in mestizo and indigenous obesity Mexican population. METHODS: We identified and characterized 50 overweight or obese subjects and 50 healthy, normal- weight volunteers with indigenous Tepehuana or Mexican mestizo ethnicity from Durango, Mexico. LEP -2548 A/G and LEPR Q223R polymorphisms were determined by genotyping. Concentrations of leptin, antioxidant capacity (CA) and lipoperoxidation (LIPX) were determined in fast conditions on plasma with Enzyme-Linked ImmunoSorbent Assay (ELISA) in all participants. RESULTS: The highest genotype frequency was the heterozygous LEPR, which was associated with lipid peroxidation levels in normal-weight Tepehuan populations. A positive correlation was observed (r = 0.5; p <0.01) between LEP polymorphism and lipoperoxidation in normal weight Tepehuan subjects. On the other hand, the LEPR polymorphism was associated with the level of lipoperoxidation (r = 0.13; P <0.05) in mestizo populations of normal weight. CONCLUSION: It is probable that there is a synergistic effect for obesity, where the presence of oxidative stress and single nucleotide polymorphisms (SNP) of leptin and its receptor contributes to the generation of pathological subcutaneous fat of obesity, together with the environmental conditions of the populations.

Skin pigmentation and genetic variants in an admixed Brazilian population of primarily European ancestry.

Although many genes have been shown to be associated with human pigmentary traits and forensic prediction assays exist (e.g. HIrisPlex-S), the genetic knowledge about skin colour remains incomplete. The highly admixed Brazilian population is an interesting study population for investigation of the complex genotype-phenotype architecture of human skin colour because of its large variation. Here, we compared variants in 22 pigmentary genes with quantitative skin pigmentation levels on the buttock, arm, and forehead areas of 266 genetically admixed Brazilian individuals. The genetic ancestry of each individual was estimated by typing 46 AIM-InDels. The mean proportion of genetic ancestry was 68.8% European, 20.8% Sub-Saharan African, and 10.4% Native American. A high correlation (adjusted R2 = 0.65, p < 0.05) was observed between nine SNPs and quantitative skin pigmentation using multiple linear regression analysis. The correlations were notably smaller between skin pigmentation and biogeographic ancestry (adjusted R2 = 0.45, p < 0.05), or markers in the leading forensic skin colour prediction system, the HIrisPlex-S (adjusted R2 = 0.54, p < 0.05). Four of the nine SNPs, OCA2 rs1448484 (rank 2), APBA2 rs4424881 (rank 4), MFSD12 rs10424065 (rank 8), and TYRP1 1408799 (rank 9) were not investigated as part of the HIrisPlex-S selection process, and therefore not included in the HIrisPlex-S model. Our results indicate that these SNPs account for a substantial part of the skin colour variation in individuals of admixed ancestry. Hence, we suggest that these SNPs are considered when developing future skin colour prediction models.

Identification of NUDT15 gene variants in Amazonian Amerindians and admixed individuals from northern Brazil.

INTRODUCTION: The nudix hydrolase 15 (NUDT15) gene acts in the metabolism of thiopurine, by catabolizing its active metabolite thioguanosine triphosphate into its inactivated form, thioguanosine monophosphate. The frequency of alternative NUDT15 alleles, in particular those that cause a drastic loss of gene function, varies widely among geographically distinct populations. In the general population of northern Brazilian, high toxicity rates (65%) have been recorded in patients treated with the standard protocol for acute lymphoblastic leukemia, which involves thiopurine-based drugs. The present study characterized the molecular profile of the coding region of the NUDT15 gene in two groups, non-admixed Amerindians and admixed individuals from the Amazon region of northern Brazil. METHODS: The entire NUDT15 gene was sequenced in 64 Amerindians from 12 Amazonian groups and 82 admixed individuals from northern Brazil. The DNA was extracted using phenol-chloroform. The exome libraries were prepared using the Nextera Rapid Capture Exome (Illumina) and SureSelect Human All Exon V6 (Agilent) kits. The allelic variants were annotated in the ViVa® (Viewer of Variants) software. RESULTS: Four NUDT15 variants were identified: rs374594155, rs1272632214, rs147390019, andrs116855232. The variants rs1272632214 and rs116855232 were in complete linkage disequilibrium, and were assigned to the NUDT15*2 genotype. These variants had high frequencies in both our study populations in comparison with other populations catalogued in the 1000 Genomes database. We also identified the NUDT15*4 haplotype in our study populations, at frequencies similar to those reported in other populations from around the world. CONCLUSION: Our findings indicate that Amerindian and admixed populations from northern Brazil have high frequencies of the NUDT15 haplotypes that alter the metabolism profile of thiopurines.

Ancient DNA Reconstructs the Genetic Legacies of Precontact Puerto Rico Communities.

Indigenous peoples have occupied the island of Puerto Rico since at least 3000 BC. Due to the demographic shifts that occurred after European contact, the origin(s) of these ancient populations, and their genetic relationship to present-day islanders, are unclear. We use ancient DNA to characterize the population history and genetic legacies of precontact Indigenous communities from Puerto Rico. Bone, tooth, and dental calculus samples were collected from 124 individuals from three precontact archaeological sites: Tibes, Punta Candelero, and Paso del Indio. Despite poor DNA preservation, we used target enrichment and high-throughput sequencing to obtain complete mitochondrial genomes (mtDNA) from 45 individuals and autosomal genotypes from two individuals. We found a high proportion of Native American mtDNA haplogroups A2 and C1 in the precontact Puerto Rico sample (40% and 44%, respectively). This distribution, as well as the haplotypes represented, supports a primarily Amazonian South American origin for these populations and mirrors the Native American mtDNA diversity patterns found in present-day islanders. Three mtDNA haplotypes from precontact Puerto Rico persist among Puerto Ricans and other Caribbean islanders, indicating that present-day populations are reservoirs of precontact mtDNA diversity. Lastly, we find similarity in autosomal ancestry patterns between precontact individuals from Puerto Rico and the Bahamas, suggesting a shared component of Indigenous Caribbean ancestry with close affinity to South American populations. Our findings contribute to a more complete reconstruction of precontact Caribbean population history and explore the role of Indigenous peoples in shaping the biocultural diversity of present-day Puerto Ricans and other Caribbean islanders.

Karyotyping and population genetics in Cold War Mexico: Armendares's and Lisker's characterization of child and indigenous populations, 1960s-1980s.

This paper focuses on geneticists Salvador Armendares's and Rubén Lisker's studies from the 1960s to the 1980s, to explore how their work fits into the post-1945 human biological studies, and also how the populations they studied, child and indigenous, can be considered laboratories of knowledge production. This paper describes how populations were considered for different purposes: scientific inquiry, standardization of medical practices, and production or application of medicines. Through the narrative of the different trajectories and collaborations between Armendares and Lisker, this paper also attempts to show the contact of their scientific practices, which brought cytogenetics and population genetics together at the local and global levels from a transnational perspective.

Karyotyping and population genetics in Cold War Mexico: Armendares's and Lisker's characterization of child and indigenous populations, 1960s-1980s / Cariotipia e genética de populações no México da Guerra Fria: as caracterizações de Armendares e Lisker sobre as populações infantil e indígena, 1960-1980

Abstract This paper focuses on geneticists Salvador Armendares's and Rubén Lisker's studies from the 1960s to the 1980s, to explore how their work fits into the post-1945 human biological studies, and also how the populations they studied, child and indigenous, can be considered laboratories of knowledge production. This paper describes how populations were considered for different purposes: scientific inquiry, standardization of medical practices, and production or application of medicines. Through the narrative of the different trajectories and collaborations between Armendares and Lisker, this paper also attempts to show the contact of their scientific practices, which brought cytogenetics and population genetics together at the local and global levels from a transnational perspective.

Resumo Aborda o trabalho dos geneticistas Salvador Armendares e Rubén Lisker, entre 1960 e 1980, para analisar como se insere nos estudos biológicos humanos do pós-1945, e demonstra como as populações estudadas por eles, a infantil e a indígena, podem ser consideradas laboratórios de produção de conhecimento. O artigo revela como as populações foram consideradas para diversos propósitos: investigação científica, padronização das práticas médicas e produção ou aplicação de suas medicinas. Por meio da narrativa das diferentes trajetórias e colaborações entre Armendares e Lisker, também procura discutir o contato de suas práticas científicas, que colocaram a citogenética e a genética de populações lado a lado nos níveis local e global a partir de uma perspectiva transnacional.