Genetic mechanisms of critical illness in COVID-19

Host-mediated lung inflammation is present 1 , and drives mortality 2 , in the critical illness caused by coronavirus disease 2019 (COVID-19). Host genetic variants associated with critical illness may identify mechanistic targets for therapeutic development 3 . Here we report the results of the GenOMICC (Genetics Of Mortality In Critical Care) genome-wide association study in 2,244 critically ill patients with COVID-19 from 208 UK intensive care units. We have identified and replicated the following new genome-wide significant associations: on chromosome 12q24.13 (rs10735079, P = 1.65 × 10 −8 ) in a gene cluster that encodes antiviral restriction enzyme activators ( OAS1 , OAS2 and OAS3 ); on chromosome 19p13.2 (rs74956615, P = 2.3 × 10 −8 ) near the gene that encodes tyrosine kinase 2 ( TYK2 ); on chromosome 19p13.3 (rs2109069, P = 3.98 × 10 −12 ) within the gene that encodes dipeptidyl peptidase 9 ( DPP9 ); and on chromosome 21q22.1 (rs2236757, P = 4.99 × 10 −8 ) in the interferon receptor gene IFNAR2 . We identified potential targets for repurposing of licensed medications: using Mendelian randomization, we found evidence that low expression of IFNAR2 , or high expression of TYK2 , are associated with life-threatening disease; and transcriptome-wide association in lung tissue revealed that high expression of the monocyte–macrophage chemotactic receptor CCR2 is associated with severe COVID-19. Our results identify robust genetic signals relating to key host antiviral defence mechanisms and mediators of inflammatory organ damage in COVID-19. Both mechanisms may be amenable to targeted treatment with existing drugs. However, large-scale randomized clinical trials will be essential before any change to clinical practice.