COVID-19, caused by the new pandemic coronavirus, is strangely—and tragically—selective. Only some infected people get sick, and although most of the critically ill are elderly or have complicating problems such as heart disease, some killed by the disease are previously healthy and even relatively young. Researchers are now gearing up to scour the patients’ genomes for DNA variations that explain this mystery.
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It’s hard to predict what will pop out from these gene hunts, some researchers say. But there are obvious suspects, such as the gene coding for the cell surface protein angiotensin-converting enzyme 2 (ACE2), which the coronavirus uses to enter airway cells. Variations in the ACE2 gene that alter the receptor could make it easier or harder for the virus to get into cells, says immunologist Philip Murphy of the National Institute of Allergy and Infectious Diseases.
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In addition to genetic variants of the ACE2 receptor, scientists want to see whether differences in the human leukocyte antigen genes, which influence the immune system’s response to viruses and bacteria, affect disease severity. And some investigators want to follow up a finding, which a Chinese team reported in a preprint: that people with type O blood may be protected from the virus.