In a standard approach to finding genes that influence a condition, geneticists scan the DNA of large numbers of people for millions of marker sequences, looking for associations between specific markers and cases of the disease. In June, one such genomewide association study in The New England Journal of Medicine (NEJM) found two “hits” linked to respiratory failure in 1600 Italian and Spanish COVID-19 patients: a marker within the ABO gene, which determines a person’s blood type, and a stretch of chromosome 3 that holds a half-dozen genes. Those two links have also emerged in other groups’ data, including some from the DNA testing company 23andMe.
