XCR1 and COVID-19: Ellinghaus et al.11 performed a genome-wide association study (GWAS) including Italian and Spanish patients with confirmed COVID-19 and controls and identified six candidate genes associated with the COVID-19 response on chromosome (chr) 3p21.31 (SLC6A20, LZTFL1, FYCO1, CXCR6, XCR1, CCR9) and one on chr 9q34.2, the locus harboring genes encoding ABO blood group antigens.