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The Neanderthal-Derived 3p21 Haplotype at LZTFL1 in Modern-Day Moroccans Is Associated With COVID-19 Severity and Further Suggests the Presence of Neanderthals in North Africa.

There is considerable variability in the clinical presentation of COVID-19 among patients infected with SARS-CoV-2. Genome-wide association studies (GWASs) have identified the 12q24.13 and 3p21.31 regions, derived from Neanderthal DNA, as the human genetic loci most strongly associated with COVID-19 severity. We examined in this study the 3p locus in the Moroccan population by analysing allele and haplotype frequencies at the LZTFL1 gene and their associations with COVID-19 outcomes. Three SNPs at LZTFL1, tagging the Neanderthal-derived COVID-19 risk haplotype, were sequenced by Sanger's method in 102 ambulatory participants and 105 hospitalized patients and have been compared to 118 controls negative for SARS-CoV-2 infection using logistic regression analysis. Results showed that the prevalence of the lead variant rs11385942 in this locus was 8.9%, whereas the variants rs35044562 and rs13078854, which tag the Neanderthal haplotype, were present in only 6.3%. Our study showed that only the rs35044562-T and rs13078854-A alleles were associated with a 2.5-fold increased risk of severe COVID-19 (p = 0.028). These two alleles, in LD with the rs11385942-AA one, form the haplotype inherited from the Neanderthal, the only haplotype associated with COVID-19 severity in the Moroccan population (p = 0.030), whereas sub-Saharan African and the rare local haplotype also containing the rs11385942 variant do not influence the COVID-19 outcomes 19 (p > 0.05). Furthermore, our study showed that the Neanderthal haplotype at 3p21 locus exists in the inhabitants of Morocco at a frequency close to that of Europeans and suggests a close connection between North Africa and Eurasia.

Adult

Comparing Neanderthal introgression maps reveals core agreement but substantial heterogeneity.

Statistical methods to identify Neanderthal ancestry in modern human genomes rest on varying assumptions and inputs. Nonetheless, most studies of introgression use only a single method to define Neanderthal ancestry. Due to a lack of "ground truth," we have a limited understanding of the accuracy, comparative strengths and weaknesses, and the sensitivity of downstream conclusions for these methods. Here, we performed large-scale comparisons of genome-wide introgression maps from 12 representative Neanderthal introgression detection algorithms. These span methods that consider archaic and human reference genomes not from Africa (ArchaicSeeker2, CRF, DICAL-ADMIX), only archaic genomes (S*, Sprime, HMM, SARGE, ARGWeaver-D), only human reference genomes, including from Africa (IBDmix), or simulated data (ArchIE). Our results highlight a core set of regions predicted by nearly all methods, as well as substantial heterogeneity in commonly used Neanderthal introgression maps. Furthermore, we find that downstream analyses may result in different conclusions depending on the map used. Thus, we recommend careful consideration of map(s) chosen for an analysis and support the use of multiple maps to ensure robustness of conclusions. We make integrated prediction sets available, enabling further understanding of Neanderthal introgression's legacy on modern humans.

Journal Article

An archaic reference-free method to jointly infer Neanderthal and Denisovan introgressed segments in modern human genomes.

Admixture between populations is a common feature of human history. Admixture events introduce new genetic variation that can fuel evolution. Characterizing the significance of admixture events on the evolution of populations across various species is of great interest to evolutionary geneticists. Local Ancestry Inference (LAI) methods infer genetic ancestry of an individual at a particular chromosomal location. Certain methods specialize in detecting archaic introgression, which consists of interbreeding between modern and archaic humans like Neanderthals and Denisovans. Most current LAI methods allow the detection of a single archaic ancestry, and post-processing may distinguish between multiple waves of introgression. These methods vary in how they choose archaic or modern reference genomes for the inference. Here, we present a new HMM-based method (DAIseg), which has the advantage of simultaneously distinguishing between multiple waves of ancient and recent admixture, using only modern human reference genomes. Simulations demonstrate that DAIseg achieves higher overall performance than state-of-the-art methods. We also apply DAIseg to Papuan populations to jointly detect Denisovan and Neanderthal introgressed segments, and identify a higher number of archaic segments than previous methods. Analysis of inferred introgressed segments, shows that we can identify evidence for two Denisovan introgression events in Papuans. Overall, on top of being able to deal with both Archaic and recent admixture, DAIseg provides a more principled approach for detecting and classifying Denisovan and Neanderthal segments which will improve downstream analysis of introgressed segments to infer the impact of archaic introgression in humans.

Denisovan

Reconstructing the 3D genome organization of Neanderthals reveals that chromatin folding shaped phenotypic and sequence divergence.

Changes in gene regulation were a major driver of the divergence of archaic hominins (AHs)-Neanderthals and Denisovans-and modern humans (MHs). The three-dimensional (3D) folding of the genome is critical for regulating gene expression; however, its role in recent human evolution has not been explored because the degradation of ancient samples does not permit experimental determination of AH 3D genome folding. To fill this gap, we apply novel deep learning methods for inferring 3D genome organization from DNA sequence to Neanderthal, Denisovan, and diverse MH genomes. Using the resulting 3D contact maps across the genome, we identify 167 distinct regions with diverged 3D genome organization between AHs and MHs. We show that these 3D-diverged loci are enriched for genes related to the function and morphology of the eye, supra-orbital ridges, hair, lungs, immune response, and cognition. Despite these specific diverged loci, the 3D genome of AHs and MHs is more similar than expected based on sequence divergence, suggesting that the pressure to maintain 3D genome organization constrained hominin sequence evolution. We also find that 3D genome organization constrained the landscape of AH ancestry in MHs today: regions more tolerant of 3D variation are enriched for introgression in modern Eurasians. Finally, we identify loci where modern Eurasians have inherited novel 3D genome folding patterns from AH ancestors and validate folding differences in a high-frequency locus using Hi-C, revealing a putative molecular mechanism for phenotypes associated with archaic introgression. In summary, our application of deep learning to predict archaic 3D genome organization illustrates the potential of inferring molecular phenotypes from ancient DNA to reveal previously unobservable biological differences.

Journal Article

Archaic ancestry inference in imputed ancient human genomes.

When modern humans expanded from Africa into Eurasia, they interbred with archaic hominins such as Neanderthals and Denisovans. This introgression shaped human evolution, yet most insights have been gained from present-day genomes, leaving little known about how archaic variants evolved after interbreeding. Ancient genomes offer a direct view of this process, but low coverage and poor quality have limited their use. Recent advances in genotype imputation offer a way to overcome these challenges by reconstructing missing information from reference panels and recovering evolutionary signals from low-coverage data. Here, we show that imputation enables accurate detection and quantification of archaic introgression in ancient genomes, improves local archaic ancestry inference, and that regions of archaic ancestry are imputed with especially high accuracy. We further demonstrate that imputed genomes can reconstruct the trajectories of introgressed haplotypes, distinguish populations across time and geography, and identify both known and additional candidates for adaptive introgression.

Humans

Transgenerational continuity: Persistence as a dimension of inheritance and evolution.

Transgenerational continuity (TC) describes the persistence of inherited molecular architectures across generations. Progress in identity-by-descent (IBD) detection, recombination dynamics, and epigenetic research highlights the growing need for a more comprehensive model of inheritance. This theoretical framework synthesizes evidence from genomics, population studies, and epigenetics to outline how inherited molecular architectures, which are transmitted through IBD, together with heritable epigenetic modifications, can preserve ancestral information across generations. IBD captures genomic continuity across three nested scales, where recent familial segments link close relatives, population-level haplotypes are shared across cohorts, and archaic fragments from Neanderthal and Denisovan admixture persist as molecular fossils of ancient lineages. Although recombination and selection reshape these regions, their persistence across time scales highlights the evolutionary durability of genomic continuity. Epigenetic memory reflects regulatory persistence, whereby molecular modifications can preserve functional states across cell divisions and sometimes across generations. Together with familial and population-level IBD persistence and the long-term retention of introgressed haplotypes, these findings demonstrate that inherited molecular architectures can persist across multiple timescales. Evolutionary processes shape this persistence. Purifying selection preferentially removes deleterious inherited variants, whereas positive selection can favor the persistence of functionally relevant genomic architectures. From this perspective, evolutionary dynamics arise not only from the generation of variation, but also from the differential persistence of inherited molecular architectures through selection. Transgenerational continuity therefore provides a conceptual framework in which persistence serves as an explanatory dimension of inheritance and evolution that complements variation and explains the persistence of biological identity across generations and evolutionary time.

Biological identity

The modern human aryl hydrocarbon receptor is more active when ancestralized by genome editing.

The aryl hydrocarbon receptor (AHR) is a transcription factor that has many functions in mammals. Its best known function is that it binds aromatic hydrocarbons and induces the expression of cytochrome P450 genes, which encode enzymes that metabolize aromatic hydrocarbons and other substrates. All present-day humans carry an amino acid substitution at position 381 in the AHR that occurred after the divergence of modern humans from Neandertals and Denisovans. Previous studies that have expressed the ancestral and modern versions of AHR from expression vectors have yielded conflicting results with regard to their activities. Here, we use genome editing to modify the endogenous AHR gene so that it encodes to the ancestral, Neandertal-like AHR protein in human cells. In the absence of exogenous ligands, the expression of AHR target genes is higher in cells expressing the ancestral AHR than in cells expressing the modern AHR, and similar to the expression in chimpanzee cells. Furthermore, the modern human AHR needs higher doses of three ligands than the ancestral AHR to induce the expression of target genes. Thus, the ability of AHR to induce the expression of many of its target genes is reduced in modern humans.

Receptors, Aryl Hydrocarbon