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One Carbon Metabolism: Expanded Polymorphism Evaluation (One_Carbon_Expan)
Principal Investigator
Research Area:
Biomedical countermeasures
Species Studied
Scientific Name: Homo sapiens Species: Human

Several crewmembers who have flown on space missions to the International Space Station have developed ophthalmic issues. This investigation evaluates genetic differences that affect enzymes in a key biochemical pathway, referred to as the “one-carbon metabolism” pathway, causing the enzymes to be less effective. This study expands upon the “One Carbon Metabolism Study” which examined five single-nucleotide polymorphisms (SNPs) and their association with a genetic predisposition for ophthalmologic issues among crewmembers. This follow-on study evaluates a wider range of SNPs to further clarify the genetic relationship to ophthalmic findings and ultimately provide a means to prevent or treat these issues in astronauts. This study recruits crewmembers who have flown long-duration missions on the International Space Station (ISS) and those who flew on one of the last three Space Shuttle missions.


  1. The primary aim is to obtain data from the 85 main genes from the total of 523 SNPs tied to one-carbon metabolism and combine findings with the existing vision and medical data available.

  2. The secondary aim is to gather and relate ethnicity data to the extent its predictive of ophthalmic problems generated during space missions.

  3. The third aim is to evaluate data from the initial and this follow-on one carbon study, to determine the mechanism that causes some individuals to be susceptible to these ophthalmic changes, and to determine treatment and prevention of these changes in crewmembers.

The research from this study has broad implications in understanding the effect of genetic influences on the one-carbon metabolism pathway, as well as in the treatment and prevention of vision and other related diseases in the general population.

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Biochemical phenomena
Intracranial pressure
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Data Information
Data Availability
Archiving in progress. Data is not yet available for this experiment.

Choroidal folds
Iron indices
Optic nerve diameter
Optic nerve sheath diameter

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 49 09/06/2016 10/30/2016 54 days
Expedition 50 10/28/2016 04/09/2017 164 days
Expedition 51 04/09/2017 06/02/2017 55 days
Expedition 53 09/02/2017 12/14/2017 102 days
Expedition 54 12/14/2017 02/27/2018 75 days
Expedition 55 02/27/2018 06/03/2018 96 days
Expedition 56 06/03/2018 10/04/2018 123 days
Expedition 57 10/04/2018 12/20/2018 77 days
Expedition 58 12/18/2018 03/14/2019 85 days
Expedition 59 03/14/2019 06/24/2019 102 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Eric Gallagher
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source
Directed Research