Genotype and Susceptibility to COVID-19

COVID-19 is a viral disease induced by infection with the novel SARS-CoV-2 coronavirus. Infection arises from the inhalation of viral particles spread by an infected individual. The main virus entry pathways are the nose and mouth mucous membranes, particularly rich in ACE2 receptors, that are used by the virus to enter cells and begin its replication. Not all individuals who contract the virus fall ill, and most of those who do (about 70-80%) experience mild symptoms (fever, cough, headache, muscle aches, loss of taste and smell). If the immune system is unable to rapidly fight the virus back, the latter can attack the lungs, affeting oxygen absorption inside the alveoli and lead to pneumonia. This more severe form is observed in 20% of patients and can develop into even more serious complications requiring intensive care, with a high mortality rate. In severe cases (about 5%), the disease spreads to the entire body reaching the cardiovascular system and brain, with the risk of heart attacks, encephalitis and stroke, but it can also affect the liver, kidney and bowel. Reasons why some subjects develop a highly severe disease while others have little or no symptoms at all still remain unclear. Many researchers are trying to find an answer by investigating the human genome, and the Mario Negri laboratories are also working in this direction. The general hypothesis underlying this research project is that inter-individual genetic variations can explain the different responses to viral infection in a population, and that COVID-19 severity is, therefore, genetically determined in each infected subject.