Therefore, ancestry is a potential confounder variable that should be considered in epidemiologic studies and in public health plans. Individual variation in relative proportions of each of these ancestries may be confounded with socio-economic factors due to population stratification. Future work in this field must commit to engaging ethically with communities of admixed origins in order to both advance knowledge and equitably distribute the benefits of genomic research to the world.Ĭurrent South American populations trace their origins mainly to three continental ancestries, i.e. We also highlight recent studies and methodological advances that have leveraged genomic signatures of admixture to gain insights into human history, natural selection, and trait architecture. We outline some of the reasons that studying admixed population genetics has been challenging in the past, including a lack of global representation in genomic panels. In this review, we discuss the trajectory of genetics research on admixed human populations in the context of Lewontin's 1972 work. This is despite a growing appreciation for the impact of admixture on shaping the genetics of contemporary human populations.
However, research aimed at unravelling the demographic history and phenotypic consequences of admixture, the genetic combination of two or more previously separated source populations, has consistently lagged behind. Over the last fifty years, geneticists have made great strides in understanding how our species' recent evolutionary history gave rise to current patterns of human genetic diversity originally observed by Lewontin in his 1972 classic, 'The Apportionment of Human Diversity'. Our findings demonstrate that future studies may also benefit from leveraging diverse ancestries and differences in linkage disequilibrium patterns to discover novel loci and additional signals with less residual population stratification. Trans-ancestral meta-analysis of the three ancestries showed a small-to-moderate impact of uncorrected population stratification on the resulting effect size estimates. Of these, 36 BMI, 124 height, and 11 WHRadjBMI SNPs were significant after trait-specific Bonferroni correction. We show that 336 known BMI, 1,177 known height, and 143 known WHRadjBMI (combined) SNPs demonstrated suggestive transferability (nominal significance and effect estimate directional consistency) in Hispanic/Latino adults. We also identified three secondary signals for BMI, 28 for height, and two for WHRadjBMI in established loci. In our trans-ancestral meta-analysis, we discovered three BMI loci, one height locus, and one WHRadjBMI locus. In our HISLA Stage 1+2 analyses, we discovered one BMI locus, as well as two BMI signals and another height signal each within established anthropometric loci. We conducted a trans-ancestral GWAS with summary statistics from HISLA Stage 1 and existing consortia of European and African ancestries. We conducted a GWAS of 18 studies/consortia as part of the Hispanic/Latino Anthropometry (HISLA) Consortium (Stage 1, n=59,771) and generalized our findings in 9 additional studies (HISLA Stage 2, n=10,538). To address this knowledge gap, we analyzed densely-imputed genetic data in a sample of Hispanic/Latino adults to identify and fine-map genetic variants associated with body mass index (BMI), height, and BMI-adjusted waist-to-hip ratio (WHRadjBMI). Hispanic/Latinos have been underrepresented in genome-wide association studies (GWAS) for anthropometric traits despite their notable anthropometric variability, ancestry proportions, and high burden of growth stunting and overweight/obesity.
Genetically estimated and self-perceived ancestry correlate significantly, but certain physical attributes have a strong impact on self-perception and bias self-perception of ancestry relative to genetically estimated ancestry. However, ancestry generally explains only a modest proportion of total phenotypic variation. Significant ancestry effects were detected for most phenotypes studied. The geographic distribution of admixture proportions in this sample reveals extensive population structure, illustrating the continuing impact of demographic history on the genetic diversity of Latin America. These individuals were also characterized for a range of physical appearance traits and for self-perception of ancestry. We estimated individual ancestry proportions in a sample of 7,342 subjects ascertained in five countries (Brazil, Chile, Colombia, México and Perú). The current genetic makeup of Latin America has been shaped by a history of extensive admixture between Africans, Europeans and Native Americans, a process taking place within the context of extensive geographic and social stratification.
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