SLC6A20 and COVID-19: The severe COVID-19-risk variants in the 3p21.31 locus contains 17 known protein-coding genes (Fig. 1c), including SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6, XCR1, CCR1, CCR3, CCR2, and CCR5. A previous TWAS using whole blood and lung eQTL datasets reported a significant association between COVID-19 severity and expression of chemokine receptor encoding genes CCR2, CCR3, and CXCR6 in lung tissue7.