WRN and Werner syndrome: In this study, utilizing a deletion null mutant Drosophila (WRNexoΔ) for the WRNexo gene encoding a protein homologous to the exonuclease domain of the human WRN gene (Bolterstein et al. 2014; Cassidy et al. 2019; Epiney et al. 2021; Gramates et al. 2022; Ozturk-Colak et al. 2024), we demonstrate that a yeast-restriction DR regimen fails to extend the lifespan of a fly model of WS.