Afro-Américains | EPFL Graph Search

Les Afro-Américains, Noirs américains ou plus rarement Africains-Américains (African Americans, Black Americans et Afro-Americans), sont une catégorie du bureau du recensement des États-Unis désignant le groupe ethnique ayant une culture et une histoire communes, que sont censés former tous les citoyens des États-Unis d'ascendance, y compris partielle, africaine subsaharienne. La grande majorité des Afro-Américains sont des descendants des esclaves déportés en Amérique septentrionale entre 1526 et 1860. Longtemps victimes de l'esclavage, de la ségrégation raciale et de la discrimination, leur déségrégation commence avec la promulgation du Treizième amendement de la Constitution des États-Unis du 6 décembre 1865 abolissant l'esclavage, du Quatorzième amendement de la Constitution des États-Unis de 1868, accordant la citoyenneté à toute personne née ou naturalisée aux États-Unis et interdisant toute restriction à ce droit, et du Quinzième amendement de la Constitution des États-Unis, d

Host genetic predictors of the kynurenine pathway of tryptophan catabolism among treated HIV-infected Ugandans

Yunfei Huang

Objective: Plasma kynurenine/tryptophan ratio, a biomarker of indoleamine 2,3-dioxygenase-1 (IDO) activity, is a strong independent predictor of mortality in HIV-infected Ugandans initiating antiretroviral therapy (ART) and may play a key role in HIV pathogenesis. We performed a genome-wide study to identify potential host genetic determinants of kynurenine/tryptophan ratio in HIV-infected ART-suppressed Ugandans. Design/methods: We performed genome-wide and exome array genotyping and measured plasma kynurenine/tryptophan ratio during the initial 6-12 months of suppressive ART in Ugandans. We evaluated more than 16 million single nucleotide polymorphisms in association with log(10) kynurenine/tryptophan ratio using linear mixed models adjusted for cohort, sex, pregnancy, and ancestry. Results: Among 597 Ugandans, 62% were woman, median age was 35, median baseline CD4(+) cell count was 135 cells/mu l, and median baseline HIV-1 RNA was 5.1 log(10) copies/ml. Several polymorphisms in candidate genes TNF, IFNGR1, and TLR4 were associated with log(10) kynurenine/tryptophan ratio (P < 5.0 x 10(-5)). An intergenic polymorphism between CSPG5 and ELP6 was genome-wide significant, whereas several others exhibited suggestive associations (P < 5.0 x 10(-7)), including genes encoding protein tyrosine phosphatases (PTPRM and PTPRN2) and the vitamin D metabolism gene, CYP24A1. Several of these single nucleotide polymorphisms were associated with markers of inflammation, coagulation, and monocyte activation, but did not replicate in a small US cohort (N = 262; 33% African-American). Conclusion: Our findings highlight a potentially important role of IFN-gamma, TNF-alpha, and Toll-like receptor signaling in determining IDO activity and subsequent mortality risk in HIV-infected ART-suppressed Ugandans. These results also identify potential novel pathways involved in IDO immunoregulation. Further studies are needed to confirm these findings in treated HIV-infected populations. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.

Lippincott Williams & Wilkins2016

A high-resolution HLA reference panel capturing global population diversity enables multi-ancestry fine-mapping in HIV host response

Jacques Fellay, Xinyi Li, Yang Luo, John Wilson

A high-resolution reference panel based on whole-genome sequencing data enables accurate imputation of HLA alleles across diverse populations and fine-mapping of HLA association signals for HIV-1 host response. Fine-mapping to plausible causal variation may be more effective in multi-ancestry cohorts, particularly in the MHC, which has population-specific structure. To enable such studies, we constructed a large (n = 21,546) HLA reference panel spanning five global populations based on whole-genome sequences. Despite population-specific long-range haplotypes, we demonstrated accurate imputation at G-group resolution (94.2%, 93.7%, 97.8% and 93.7% in admixed African (AA), East Asian (EAS), European (EUR) and Latino (LAT) populations). Applying HLA imputation to genome-wide association study data for HIV-1 viral load in three populations (EUR, AA and LAT), we obviated effects of previously reported associations from population-specific HIV studies and discovered a novel association at position 156 in HLA-B. We pinpointed the MHC association to three amino acid positions (97, 67 and 156) marking three consecutive pockets (C, B and D) within the HLA-B peptide-binding groove, explaining 12.9% of trait variance.

NATURE PORTFOLIO2021

Examining African contributions to global health: Reflections on knowledge circulation and innovation

Jérôme Chenal, Akuto Akpedze Konou, Vitor Pessoa Colombo, Julia Tischler

This article unites different disciplinary debates on ‘southern innovation’, ‘theory from the South’, and ‘decolonisation of knowledge’ in order to discuss existing understandings around the role of Africa in the production of health-related knowledge, public health policy, and medical innovation. Arguing that high-income countries have much to learn from the global South when it comes to health-related knowledge and practices, we propose an interdisciplinary research approach to uncovering and examining African contributions to global health, drawing on an ongoing collaborative project funded by the Swiss National Science Foundation. We present four empirical case studies concerning drug development, healthcare systems, and urban planning to critically enquire into both historical and contemporary transcontinental knowledge circulation and learning potentials, as much as cases of forgetting and silencing. On this basis, we argue that ‘learning from the South’ must mean more than transplanting quick and cheap technological fixes to serve societies in the global North, but rather recognising the vast contributions that Africans have made to global epistemologies, without losing sight of the asymmetries inherent in South–North knowledge exchanges. Lessons learned might apply to fields other than those discussed here and go far beyond ‘reverse innovation’.

2022

Host genetic predictors of the kynurenine pathway of tryptophan catabolism among treated HIV-infected Ugandans

Yunfei Huang

Lippincott Williams & Wilkins2016