COVID19: Genetic factor increases the risk of loss of smell and taste

Many of the people with COVID-19 show a loss or reduction of smell or taste. Up to 80% of people who are coronavirus positive report that food and drink taste different than usual or that they do not taste good or that they cannot smell well. This usually lasts for a few weeks. But there are some, about 1,6 million people in the US, where there is evidence that they still can not smell properly for more than 6 months after infection. According to a new study, recently published in the prestigious international scientific journal Nature Genetics, a specific genetic factor has been found that increases the risk of loss of smell and taste due to COVID-19.

The doctors of the Therapeutic Clinic of the Medical School of the National and Kapodistrian University of Athens, Stavroula Paschou (Assistant Professor of Endocrinology), Theodora Psaltopoulou (Professor of Therapeutic-Epidemiology-Preventive Medicine) and Thanos Dimatopa-Prof. results of this study.

Researchers analyzed data from nearly 70.000 people who tested positive for coronavirus. Among them, 68% reported loss of smell or taste as a symptom. Using modern genetic techniques and intelligent statistical models, multiple possible genetic differences were studied between those who lost their sense of smell and taste and those who retained them. A specific genetic locus close to two olfactory genes, UGT2A1 and UGT2A2, has been found to be associated with loss of smell and taste due to COVID-19. This genetic risk factor gives an 11% higher chance to a person with COVID-19 to lose the sense of smell or taste. The research team also found that women were 11% more likely than men to report a relative loss. Also, about 73% of those who reported loss of smell or taste were aged 26-35 years.

Researchers are still unsure of the exact mechanisms. Typically, these genes are expressed in the olfactory mucosa, where they are involved in the breakdown of chemicals and the processing of signals that lead to the sense of smell. It seems that the nerve pathways that cause smell and / or taste may be genetically hyperfunctional or hypofunctional in some people. If cells are infected with a coronavirus, then, genetic predisposition significantly determines their resistance to reducing or deforming their ability to taste and smell.

Previous research has shown that loss is associated with the inability to protect the sensory cells of the nose and tongue from viral infection. This new study, as noted by the professors of EKPA, proposes a different genetic direction and its findings could even contribute to the discovery of new therapies.

Source: RES-EAP