The goal of this proposal is to delineate the risk of CH for astronauts and other patients using improved, novel methods that map nucleic acids isolated from peripheral blood and urine. We hypothesize that radiation imparts a selective advantage, specifically in hematopoietic cells with DNA Damage Response mutations, and that spaceflight duration and radiation dose can drive and mediate this selection process.

We will use a cohort of >1,100 patients from Weill Cornell Medicine (WCM) with both blood and urine, where 11% already show CH, as well as existing data from healthy cohorts (n=20,000) from the Englander Institute for Precision Medicine (EIPM) and Memorial Sloan Kettering Cancer Center (MSKCC) (n=25,000). We will use established methods for purifying and extracting DNA, using protocols developed for the NASA Twins Study and our published EIPM PreCISE-1 test for CH. This includes 100+ genes involved in clonal hematopoiesis, cancer, and cardiovascular diseases (CVD), sequenced to a depth of >2000x coverage (with unique molecular barcodes), giving >95% sensitivity for variant allele frequencies (VAF) > 1% (about 1/50 cells).

The presence of CH can inform long-term CVD and cancer risk, and thus can serve as a useful metric for astronauts preparing for long-term missions. Also, CH confers a mutation-specific inflammatory risk, which can potentiate post-flight or post-radiation morbidity and be compared to other risk factors. Thus, identifying and managing CH represents a crucial unmet need for astronaut health, radiation risk stratification, and guiding oncology patients more broadly.