23andMe reported genetic associations tied to how patients respond to GLP-1 receptor agonists, identifying variants that map to pharmacodynamic target genes. In a Nature study, investigators analyzed survey responses and array genotypes from 27,885 consented participants and reported a missense GLP1R variant linked to enhanced medication response, alongside GLP1R and GIPR variants associated with nausea and vomiting. The results were used to build a model that could stratify individuals based on expected efficacy and side-effect risk using electronic health record inputs. The study’s effect sizes were described as modest so far, with improved predictive utility expected as additional genetic associations are uncovered. A separate genetic analysis also points to inter-person variability in GLP-1 weight loss benefits, reinforcing that target-pathway genetics may explain part of the observed differences in clinical outcomes and tolerability.