Fig. 6: Adaptation and archaic introgression at COVID-19-associated (r)eQTLs.

a–d, Features of (r)eQTLs colocalizing with COVID-19 risk loci (PP_H4 > 0.8) and presenting either strong population differentiation (top 1% PBS genome-wide) or evidence of Neanderthal introgression. a, Effects of the target allele on gene expression across immune lineages and stimulation conditions. b, Clinical and functional annotations of associated genes. c, Present-day population frequencies of the target allele. d, The effects of the target allele on COVID-19 risk (infection, hospitalization and critical state), colocalization probability and the lineage and condition in which gene expression most likely affects COVID-19 risk as detected by transcriptome-wide association (TWA) analyses. For expression or COVID-19 associations, the arrows indicate increases/decreases in expression or disease risk with each copy of the target allele, and the opacity reflects the strength of association (two-sided Student’s t-test −log₁₀[P]). For the TWA analysis, the arrows indicate the effect of an increase in gene expression on the risk of COVID-19. In a and d, the arrow colours indicate stimulation conditions (non-stimulated (grey), SARS-CoV-2-stimulated (red), IAV-stimulated (blue)) and the background colour indicates the lineage (myeloid (pink), B (purple), CD4⁺ T (blue), CD8⁺ T (green), NK (light green)). For each eQTL, the target allele is defined as (1) the derived allele for highly differentiated eQTLs or (2) the allele that segregates with the archaic haplotype for introgressed eQTLs. When the ancestral state is unknown, the minor allele is used as a proxy for the derived allele. Note that, in some cases (for example, OAS1), the introgressed allele can be present in Africa, which is attributed to the reintroduction in Eurasia of an ancient allele by Neanderthals⁴⁶. C, critical; H, hospitalized; R, reported.