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People With This Mutation Can’t Smell Stinky Fish

Most people carry an intact version of TAAR5, and easily recognize the fishy fragrance as mildly repulsive — an ability that might have evolved to help our ancestors avoid spoiled food. But a small number of the Icelanders in the study carried at least one “broken” copy of the gene that appeared to render them insensitive to the scent. When asked to describe it, some even mistook it for a sugary dessert, ketchup or something floral.

“They were really not even in the right ballpark,” Dr. Gísladóttir said.

A blunted sense for bad-smelling fish might sound maladaptive. But TMA doesn’t always spell trouble, especially in Iceland, where fish features prominently on many menus. The country is famous for nose-tickling dishes like rotten shark and fermented skate, which serve up about as much odor as you may imagine.

That might be why the TAAR5 mutation appears in more than 2 percent of Icelanders, but a much smaller proportion of people in Sweden, Southern Europe and Africa, the researchers found.

“If they hadn’t looked at this population, they might not have found the variant,” said Bettina Malnic, an olfaction expert at the University of São Paulo in Brazil who was not involved in the study.

Paule Joseph, an expert in sensory science at the National Institutes of Health, noted that these genetic changes could affect, or be affected by, dietary patterns. “It would be good to see a similar study in another population and more diverse group of individuals,” Dr. Joseph said.

Dr. Stefánsson said it’s a shame he doesn’t carry the rare mutation, considering how much cod liver oil he had to swallow as a child at the behest of his mother. Still, he eventually figured out a way to escape the chore.

“I told my mother, ‘I’m not going to have another spoon unless you do it yourself,’” he recalled. “I never took cod liver oil again.”

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People With This Rare Gene Mutation Can’t Smell Fishy Scents


  • Researchers conducted a smell test on over 9,000 participants 
  • Some of them couldn’t detect the fish scent or had a less intense experience 
  • Researchers found for these people the fish’s off-putting odor might smell even like caramel

A new study has revealed a genetic mutation that makes people who carry it be less susceptible to the smell of fish. For some of these people, fish’s off-putting odor might even smell like caramel or roses. 

Humans perceive smells using olfactory receptors, but of the 855 olfactory genes, about half are actually not functional. The reasons for this and why people have a “highly personalized” sense of smell remain a mystery.

To shed light on the matter, the researchers of a new study conducted a smell test wherein they presented 9,122 participants in Iceland with various smells including fish, cinnamon and liquorice, then asking them to name it and rate the pleasantness and intensity.

Overall, fish scent was rated as the least pleasant, but a small number of the participants had a somewhat different perception of the fishy smell.

The researchers found people with a mutation in a receptor gene called trace anime-associated receptor 5 (TAAR5) perceived the fish odor with trimethylamine (TMA) as a main ingredient as less intense. For instance, when presented with the smell of fish, those with the variant described it as having the smell of “caramel” or “rose” instead of other fishy odors such as “fermented skate” or “shark.” Some could not even recognize the scent at all.

On the other hand, those with an intact version of TAAR5 easily recognized the fishy scent.

“Carriers of the variant find the fish odor less intense, less unpleasant, and are less likely to name it accurately,” study first author Rosa Gisladottir of deCODE Genetics in Iceland said in a Cell Press news release.

Exactly how this variant affects the odor perception of people with the mutation is still unclear. 

TMA is also found in animal odors and human body secretions such as urine, blood and sweat.

Fish Pictured: Representative image of a crate of fish at a market. Photo: Pixabay

Additionally, the researchers also identified other variants that affected people’s ability to perceive the scent of liquorice and cinnamon. In this case, the participants found the scents to be more intense but also more pleasant.

These particular variants are distributed differently across the globe — 57% in East Asia and 11% in Europe.

“Spices containing trans-anethole, the main ingredient in the licorice odor, are widely used in Asian cuisine and traditional medicine,” the researchers wrote. “It could be speculated that variants associated with the perception of trans-anethole licorice odor conferred some advantage in East Asia, leading to the large frequency differences between populations.”

The study showed that even if humans do have reduced olfactory genes, the differences in variants make the sense of smell quite diverse.

“Altogether, our results provide a unique window into the effects of sequence diversity on human olfaction,” the researchers wrote. “An individual’s personalized

Tillis, positive for virus, regains taste, smell

WASHINGTON (AP) — The Latest on President Donald Trump’s health after his COVID-19 diagnosis and hospitalization, and infections of close aides and others (all times local):

5:20 p.m.

Republican Sen. Thom Tillis of North Carolina says he’s regained his sense of taste and smell after testing positive for the coronavirus last week.

Tillis tweeted Monday: “I feel great.” He says that although he’s no longer exhibiting any symptoms of the coronavirus, he will continue to self-isolate.

Tillis is among several people who tested positive for the virus days after attending the Supreme Court nomination ceremony for Amy Coney Barrett at the White House on Sept. 26. Others who came down with the coronavirus include President Donald Trump and Republican Sen. Mike Lee of Utah.

Tillis was wearing a mask during the outside ceremony and has supported mask use. A New York Times photo taken inside the White House showed a maskless Tillis speaking to Barrett.

Tillis is in a tight race for reelection in November. He has temporarily halted in-person campaigning, and several campaign staff went into quarantine.


4:40 p.m.

Washington, D.C., officials say the White House has rebuffed their offers to assist with contact tracing after President Donald Trump and several others who attended a Rose Garden event to introduce the new Supreme Court nominee tested positive for COVID-19.

Democratic Mayor Muriel Bowser says a D.C. health department representative who reached out to the White House “had a very cursory conversation that we don’t consider a substantial contact from the public health side.”

Washington’s local virus regulations don’t apply on federal property, and the White House has hosted multiple gatherings that exceeded the local 50-person limit, and many participants didn’t wear masks.

The Sept. 26 ceremony announcing Trump’s nomination of Amy Coney Barrett is now regarded as a potential infection nexus.

The White House says it is doing contact tracing, and “appropriate notifications and recommendations are being made.”


3:50 p.m.

President Donald Trump is planning to return to the White House on Monday evening, but doctors couldn’t say when he’ll no longer be contagious for the coronavirus or when he’d be able to travel again.

The president’s personal physician, Dr. Sean Conley, told reporters at Walter Reed National Military Medical Center on Monday afternoon that Trump is not out of the woods yet, but that there is no care at the hospital that the president cannot get at the White House.

Typically, COVID-19 patients don’t have tests when they leave the hospital. Doctors says Trump will be given advanced testing that is not readily available to determine when no more viable virus is present.

Trump announced his coronavirus diagnosis early Friday and spent three days in the hospital.


3:45 p.m.

An infectious-disease specialist says he’s working with President Donald Trump’s medical team on infection control strategies so that the president can return to the White House.

Dr. Jason Blaylock said Monday that he’s working closely with local laboratories to obtain advanced diagnostic testing that would inform