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Many corona infected people can no longer perceive the scent of roses
Photo: Roland Weihrauch/ dpa
Being unable or hardly able to smell (and thus taste) is one of the most common signs of an infection with the Sars-Cov-2 coronavirus - unpleasant, but also with potentially serious consequences.
The exact cause of this olfactory disorder has not yet been clarified.
Who it hits could be partly genetically determined.
A team led by Janie Shelton from the US genetic analysis company 23andMe has narrowed down the hereditary factors likely to be responsible.
The study, which was first reported on by the portal wissenschaft.de, was published in the journal »Nature Genetics«.
The researchers noticed that people of European descent reported the symptom significantly more often than people with African or Asian ancestry.
Overall, they examined the genetic data of 69,841 people from the US and UK who tested positive for the coronavirus.
68 percent of them reported an odor or taste disorder, women more often than men and younger infected people more often than older ones.
In the gene database, the complete genomes of the test subjects were now examined for possible connections. Four different phenotypes of people with a specific mix of genetic traits could be identified. It was known from previous studies that one of them was more likely to have vanilla as their favorite ice cream flavor, and another to be more prone to smoking tobacco.
Around the genes UGT2A1 and UGT2A2, there was a statistically significant accumulation with an 11 percent increased probability of the smell and taste disorder. According to the study, these two genes are "not only the closest, but also the biologically most plausible gene candidates." It is already known that these genes play a role in the formation of the sense of smell. They ensure the formation of enzymes, which animal experiments have shown that they make odorous substances disappear from the receptors and thus prevent the perception of the smell in the brain. The results are particularly pronounced among people of European origin, but are valid in all groups.
Jamie Shelton and colleagues refer to recent research, according to which the smell disorder can be explained by a viral infection of the olfactory epithelium (a mucous membrane at the top of the nasal cavity) and destruction of the cilia - not a direct infection of the nervous system.
However, the neurons responsible for smelling are affected when the supporting cells in their vicinity stop producing the necessary proteins.
How exactly this process works can be better researched with the help of the new genetic knowledge.
a.k
