Did a NASA astronaut's DNA change after one year in space?

Robert Markowitz

In a statement Thursday, NASA clarified that Scott and Mark Kelly are still identical twins.

To better understand the potential health impact of a year of weightlessness in space, NASA conducted a groundbreaking study comparing Kelly to his identical twin brother Mark, a retired astronaut who remained here on Earth.

The Twins Study brought 10 research teams from around the country together to accomplish one goal: discover what happens to the human body after spending one year in space. According to NASA's research - which is still preliminary, with the agency expecting to publish a more complete study this year - it's not Kelly's genes that changed but how they were expressed.

Live Science reported that 7 percent of astronaut Scott Kelly's DNA changed when he was in space. This information was originally discovered past year; however, NASA confirmed the findings just a few weeks ago after noticing that Scott's telomeres shortened after he landed.

Kelly said he was surprised by that change in a recent interview with Marketplace. With this study, we've seen thousands and thousands of genes change how they are turned on and turned off.

"Although 93% of Scott's genetic expression returned to normal once he returned to Earth, a subset of several hundred "space genes" remained disrupted", the publication explains.

The transformation of 7% of Scott's DNA suggests longer-term changes in genes related to at least five biological pathways and functions.

The Kelly brothers have almost identical genomes, allowing for an unprecedented look at the physical effects of long-term spaceflight.

Kelly spent 340 days on the International Space Station in 2015 to 2016, along with Russian crewmate Mikhail Kornienko. "So that would make a major change in how we think about exploring the solar system, exploring space, and a change in understanding who we are and what we can do as explorers".

Nasa collected regular readings for metabolites, cytokines and proteins and discovered that spaceflight was linked to oxygen deprivation stress, increased inflammation and dramatic nutrient shifts which affect genes.

The changes occurred in Kelly's telomere - a cap of genetic material at the end of each chromosome. First, there was a significant increase in average length while he was in space, and then there was a decrease in length within about 48 hours of his landing on Earth that stabilized to almost preflight levels. Additionally, a new finding is that the majority of those telomeres shortened within two days of Scott's return to Earth. However, it does give researchers further insights into how the body reacts to space.