De new research led by a professor inIcahn School of Medicine at Mount Sinai (USA) states that the genomes of the 14 astronauts who performed missions aboard the US Space Shuttle between 1998 and 2001 show the same genetic mutations. These were characterized by a high proportion of blood cells derived from a single parent cell, a phenomenon called clonal hematopoiesis (Clonal hematopoiesis).
Caption Image: NASA astronaut Steven L. Smith servicing the Hubble Space Telescope during the 22nd mission of the Space Shuttle Discovery in 1997. (NASA)
These mutations, the team explains, are small in magnitude and unlikely to pose a serious threat to the astronauts’ long-term health. Despite this, the research points to the importance of regular health screening of space travelers, especially those going on long journeys, including monitoring for changes in their DNA.
Mutations of the type identified in this study can be caused by exposure to ultraviolet (UV) light, the team explains, as well as other forms of radiation. They are usually seen in patients undergoing radiation therapy or chemotherapy for cancer.
In this particular case, the most likely suspect is ambient radiation present in space, the team adds.
According to the lead author, David Goukassian, professor of medicine atIcahn School of Medicine at Mount Sinai :
Astronauts work in an extreme environment where many factors can lead to somatic mutations, the most important of which is space radiation, which means that there is a risk of these mutations turning into clonal hematopoiesis.
Last year, NASA proposed changing the amount of radiation it believes astronauts can safely be exposed to to better protect their health. This is to allow older astronauts to be exposed to a relatively lower level of radiation than younger ones, and to eliminate the different limits for men and women.
The blood samples used in this study were obtained from 12 male and 2 female astronauts, and they were collected ten days before the flight and on the day of landing. They were then cryogenically preserved for about two decades.
According to Goukassian:
Although the clonal hematopoiesis we observed was relatively small in size, the fact that we observed these mutations was surprising given the relatively young age and health of these astronauts. The presence of these mutations does not necessarily mean that astronauts will develop cardiovascular disease or cancer, but there is a risk that this may occur over time due to continued and prolonged exposure to the extreme environment that is deep space.
Age plays a role here, as this type of mutation resembles one that occurs spontaneously in older people. That said, the median age of the astronauts in this study was only 42.
Based on these findings, Goukassian and his team recommend that NASA regularly screen astronauts for these types of mutations. Initially, this would better protect their health, but in the long term these measures would also provide more data and a better understanding of the risks spaceflight poses to human biology.
The study published in Nature Communications Biology: Retrospective Analysis of Somatic Mutations and Clonal Hematopoiesis in Astronauts and presented on the website ofIcahn School of Medicine at Mount Sinai : Scientists find that spaceflight may be linked to DNA mutations and increased risk of developing heart disease and cancer.