Astronaut Scott Kelly’s DNA no longer matches identical twin’s after a year in space, NASA says
Scott Kelly was stationed on the International Space Station leaving his brother Mark on Earth

AN astronaut's DNA no longer matches his identical twin's after a year in space, a study by NASA confirmed.
Scott Kelly was stationed on the International Space Station from March 2015 to March 2016, leaving his brother Mark - a retired astronaut - on Earth.
Researcher's found that seven percent of Scott's genes didn't return to normal after he got back from space two years ago.
Publishing its latest findings, NASA said the formerly identical twins are not longer genetically the same.
Writing on Twitter about the findings, Scott joked: "This could be good news! I no longer have to call @ShuttleCDRKelly my identical twin brother anymore."
The brothers, both aged 54, took part in the study using extensive comparisons to find out exactly what happens to the body before, during and after a year in space.
Scientists measured the men's metabolites, which are necessary for maintaining life; cytokines, which are secreted by immune system cells; and proteins, the workhorses within each cell.
Researchers learned that spaceflight is associated with oxygen deprivation stress, increased inflammation, and dramatic nutrient shifts that affect gene expression.
After returning to Earth, Scott started the process of re-adapting to Earth’s gravity and most of the biological changes he experienced in space quickly returned to nearly his pre-flight status - some within hours and others in about six months.
Researchers say that in all, 93 percent of Scott's genes returned to normal after landing, but the remaining seven percent could point to possible longer-term changes.
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It relates to five biological pathways and functions, including his immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia.
Last year, NASA published its first round of results from the Twins Study at the Investigator's Workshop for Human Research Program - and the findings this year largely corroborated them.
Scott's one-year trip to ISS - which was six months longer than any other astronaut - is a stepping stone to a three-year mission to Mars, NASA says.
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