NADH is a metabolic cofactor that, along with its oxidized form, NAD+, participates in hundreds of reduction/oxidation (redox) reactions that power cellular metabolism. A relative increase in NADH levels promotes reduction and is thought to be a source of metabolic stress (“reductive stress”), though the precise consequences of reductive stress in vivo have been difficult to study due to a lack of tools with which to precisely manipulate NADH levels. Using a newly developed tool that enables precise tissue- specific manipulation of NADH, we recently demonstrated that the metabolite -hydroxybutyrate was a biomarker of hepatic reductive stress, and that hepatic reductive stress was causally linked to a number of important metabolic traits. The long-term goal of this work to better understand the genetic architecture of hepatic reductive stress, and in doing so both expand our understanding of its metabolic and physiologic consequences and to identify potential genes that might be targeted to alter metabolism in beneficial ways. Our central hypothesis is that genetic regulators of hepatic reductive stress can be identified in the diversity outbred (DO) mouse cohort by combining existing genotyping and RNAseq data with measurements of mouse plasma -hydroxybutyrate levels. The rationale for this proposal is that, having demonstrated that reductive stress influences many important metabolic traits, identifying genetic regulators of reductive stress will provide key regulators of this important metabolic parameter and is significant as this will inspire novel therapeutic targeted paradigms. This work is innovative in that it leverages new insight that plasma -hydroxybutyrate is biomarker of hepatic NADH levels to use plasma from a genetically diverse mouse cohort to identify causal genetic influences of this parameter.