Scott Kelly: Twin Study Reveals Astronaut’s DNA Changed After Spending One Year In Space

Scott Kelly spent a year aboard the International Space Station between March 2015 and 2016. According to a twin study, which was conducted by geneticists under the direction of NASA, Scott experienced unusual changes in his DNA methylation, gene expression, and other biological markers during his year in space.

The ISS One-Year Mission was a scientific research project, which was designed to identify the effects of long-term space travel on an astronaut’s body and mind.

The project was a joint effort between NASA and the Russian Federal Space Agency, who each sent one experienced crew member to live aboard the ISS for one year. United States native Scott Kelly and Russian native Mikhail Korniyenko both agreed to undergo a series of mental and physical testing before, during, and after the year-long mission.

The mission also provided NASA with a unique opportunity to perform a twin study with Scott Kelly and his brother Mark — who was not part of the mission.

To conduct the twin study, geneticists collected blood and other biological samples from Scott Kelly and his identical twin before, during, and after the ISS One-Year Mission. Although the study is not complete, the geneticists already noted marked changes in Scott’s DNA methylation, gene expression, and other biological markers.

Colorado State University radiation biologist Susan Bailey said one of the more interesting changes involved the length of Scott Kelly’s telomeres.

As reported by Nature, telomeres are protective “caps,” which are found on the ends of a chromosome. As a rule, telomeres shorten as we grow older and subsequently provide less protection to the cells.

Interestingly, Scott Kelly’s white blood cell telomeres increased in length during his stay on the ISS. However, the twin study revealed the length of his brother’s telomeres did not change.

Scott’s telomeres eventually returned to their pre-mission length, but geneticists are still interested in the temporary increase. A series of studies will be conducted on “ten unrelated astronauts” over the next two years to determine whether they experience the same anomaly during spaceflight.

Johns Hopkins University School of Medicine geneticist Andrew Feinberg said the twin study revealed Scott Kelly and his brother both experienced DNA methylation, or chemical modifications, during the mission.

As reported by Science Daily, Scott’s DNA methylation decreased during the ISS One-Year Mission, whereas Mark’s DNA methylation increased during the same period of time. Interestingly, both men’s DNA methylation values “returned to normal” after Scott returned from the mission.

The twin study also revealed Scott Kelly and his brother experienced “changes in gene-expression signatures” during the year-long mission. Nature reports changes in gene-expression signatures are not unusual. However, “the changes in Scott seemed to be larger than normal.”

The geneticists who are working on Scott Kelly’s twin study acknowledge the anomalies could be attributed to differences in the twins’ diet, exercise, stress levels, and the unique environment aboard the ISSl. However, they believe the findings are significant enough to justify further studies.

Although a small portion of the results was released, the geneticists said it could take years to complete the study. It is unknown whether the full results of the twin study will be made available to the public, as they could reveal “sensitive data” that Scott and Mark would prefer “to keep private.”

As reported by NASA, Scott Kelly’s twin study was part of the agency’s Human Research Program, which strives to reduce “the risks to human health and performance through a focused program of basic, applied, and operational research.” The results of the twin study, and similar research, are expected to help scientists reduce the mental and physical risks associated with long-term space travel.

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