Comprehensive Measurement of Inter-Individual Variation in DNA Repair Capacity in Healthy Individuals

Rare genetic DNA repair deficiency syndromes can lead to immunodeficiency, neurological disorders, and cancer. In the general population, inter-individual variation in DNA repair capacity (DRC) influences susceptibility to cancer and several age-related diseases. Genome wide association studies and functional analyses show that defects in multiple DNA repair pathways jointly increase disease risk, but previous technologies did not permit comprehensive analyses of DNA repair in populations. To overcome these limitations, we used fluorescence multiplex host cell reactivation (FM-HCR) assays that directly quantify DRC across six major DNA repair pathways. We assessed DRC in phytohemagglutinin-stimulated primary lymphocytes from 56 healthy individuals and validated assay reproducibility in 10 individuals with up to five independent blood draws. We furthermore developed generalized analytical pipelines for systematically adjusting for batch effects and both experimental and biological confounders. Our results reveal significant inter-individual variation in DRC for each of 10 reporter assays that measure the efficiency of distinct repair processes. Our data also demonstrate that correlations between the activities of different DNA repair pathways are relatively weak. This finding suggests that each pathway may independently influence susceptibility to the health effects of DNA damage. We furthermore developed a pipeline for analyzing comet repair kinetics and related our new functional data to previously reported comet assay data for the same individuals. Our pioneering analysis underscores the sensitivity of FM-HCR assays for detecting subtle biological differences between individuals and establishes standardized methodologies for population studies. Our findings and open source analytical tools advance precision medicine by enabling comprehensive exploration of genetic, demographic, clinical, and lifestyle factors and supporting targeted interventions to enhance DNA repair and maintain genomic integrity, thereby promoting personalized healthcare and disease prevention.