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According to a new study published in the journal Nature Genetics, an underlying genetic risk factor could explain why certain people lose their senses for smell and taste when they are infected with COVID-19.
The findings could aid the 1.6 million people in the U.S. who still can’t smell or have had an improvement in their ability to smell for more than six months after contracting the coronavirus. Researchers believe COVID-19 could be caused by damage to the olfactory epithelium, which is a component of the nose.
“How we get from infection and loss of smell remains a mystery,” Justin Turner, MD an associate professor of Otolaryngology at Vanderbilt University, , said to NBC News. Turner did not participate in the research team.
“Early research suggests that the supporting cells of the olfactory epithelium are ones most affected by the virus, and presumably this leads to the death of neurons,” he said. “But we don’t know why or when it happens or why it appears to preferentially occur in certain people.”
23andMe, a biotech and genomics firm, conducted the study as a part of the larger COVID-19 Project, which included people in the U.S., and the U.K. They analyzed data from nearly 70 thousand people who took online surveys after receiving a positive coronavirus test. Among those 68% of those who took part, 68% reported loss of smell or taste as a sign of.
The researchers compared genetic differences between people who lost their senses of smell and taste to determine which group had more genetic differences. The team’s study revealed that COVID-19 loss of taste and smell was associated with a location near two of the smelly genes UGT2A1 or UGT2A2. COVID-19 sufferers are 11% more likely to experience a loss of taste or smell due to the genetic risk factor.
The team of researchers also found that women were 11% more likely than men to experience the loss of taste and smell. Around 73% of those who reported losing smell and taste were ages 26-35.
The researchers aren’t sure how the genes are involved, but they believe that infected cells could lead to smell loss. Typically, the genes are expressed in the tissues of the nose that is involved in smell and play a role in the processing of things with an smell. To make use of these findings, researchers need to understand the genes, how they are expressed and what their purposes are, NBC News reported.
These findings could lead to the development of new treatments. Another study has demonstrated that loss of taste or smell is caused by the “failure of protecting sensory cells in the tongue and nose against virus infection,” Danielle Reed PhD, associate director at the Monell Chemical senses centre in Pennsylvania said to NBC News. She wasn’t part of the research team but she is a researcher who studies person-to-person differences in loss of these senses as a result of COVID-19.
“This study suggests an alternative direction,” she said. “The pathways that break down the chemicals that trigger taste or smell might be too active or inactive to limit or alter the ability to taste or smell.”
Sources:
Nature Genetics : “The UGT2A1/UGT2A2 locus could be associated with COVID-19-related smell , or loss of taste.”
NBC News: “Genetic risk factor for Covid-19’s smell and taste loss, researchers say.”
