CCR9 and COVID-19: Also, recently, it was found that a region of our DNA situated on chromosome 3 (locus 3p21.31), spanning a length of 49.3 kb, consisting of 6 genes (SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6, and XCR1), was associated with the risk of developing severe COVID-19 [34].