Scientists have found no long-lasting, major epigenetic differences in astronaut Scott Kelly, who spent a year in space aboard the International Space Station (ISS), and his twin brother, Mark Kelly, who remained on Earth. Epigenetic changes involve chemical “tweaks” to DNA that can influence gene activity, but the changes don’t affect the underlying genetic code itself. The changes affect when and how a gene is read, or expressed, for its protein-encoding instructions.
Andrew Feinberg from the Johns Hopkins University in the US said that the study is the dawn of human genomics in space and they developed the methods for doing these types of human genomic studies to draw conclusions about what happens to humans in space. Scientists have long monitored and studied the physiological effects of space travel on astronauts.
However, most of these astronauts travel on spaceflight missions of six months or less, not the longer missions required to travel to Mars or elsewhere. Feinberg noted that studying identical twins — who, by nature, have the same genetic material — was an important and rare opportunity to compare physiological and genomic changes when one twin went into space and the other remained on Earth.