Genotype, B-vitamin status, and androgens affect spaceflight-induced ophthalmic changes

Area of Science:

• Space medicine
• Human physiology
• Genetics

Background:

• Ophthalmic changes and visual deterioration are significant risks for astronauts during spaceflight.
• Elevated preflight 1-carbon metabolites, such as homocysteine, are observed in astronauts experiencing vision issues.

Purpose of the Study:

• To investigate the association between genetic variations in 1-carbon metabolism genes and the susceptibility to ophthalmic changes in astronauts.
• To identify specific gene polymorphisms that predict vision alterations after space missions.

Main Methods:

• Studied 5 polymorphisms in methionine synthase reductase (MTRR), methylenetetrahydrofolate reductase (MTHFR), serine hydroxymethyltransferase (SHMT), and cystathionine β-synthase (CBS) genes.
• Analyzed ophthalmic changes in 49 astronauts post-International Space Station missions.
• Utilized block regression to assess the predictive power of B-vitamin status and genetics on ophthalmic outcomes.

Main Results:

• The G allele of MTRR 66 and the C allele of SHMT1 1420 were associated with an increased likelihood of visual disturbances.
• Preflight dehydroepiandrosterone levels correlated with cotton wool spots, and in-flight testosterone response was linked to refractive changes.
• B-vitamin status and genetic factors were significant predictors of various post-flight ophthalmic outcomes, with B-vitamin status significantly improving predictive models for refractive change.

Conclusions:

• Specific polymorphisms in MTRR (rs1801394, MTRR 66) and SHMT1 (rs1801133, SHMT1 1420) are associated with spaceflight-induced vision changes.
• Genetic predisposition and B-vitamin status are crucial factors in astronaut vision health during spaceflight.
• This research may pave the way for therapeutic interventions for vision problems in both astronauts and the general population.