86: Why Pathogenic Variant Impact Varies: Variant Effects, Polygenic Background, and Epistasis

Nature Communications - A biobank-scale study using UK Biobank and Mount Sinai BioMe exomes examines three genetic contributors to incomplete penetrance and variable severity of monogenic cardiometabolic variants: heterogeneous missense variant effects, additive polygenic background, and marginal epistasis between carrier status and common variation. Key terms: variant pathogenicity, polygenic risk score, marginal epistasis, ESM1b, biobank exomes. Study Highlights:The authors applied the ESM1b protein language model to show that missense variant pathogenicity scores predict phenotype severity for carriers in multiple genes and distinguish gain- from loss-of-function variants. Polygenic risk scores independently modify phenotypes among pathogenic carriers, with noncarriers in PRS tails sometimes exceeding carriers in severity. Using the FAME method, they detected significant marginal epistasis modifying carrier effects for LDL, triglycerides, and MODY, with epistatic improvement percentages up to 170%. Findings were supported by replication in the BioMe cohort and expanded UKB exomes. Conclusion:Variant-level effect heterogeneity, polygenic background, and marginal epistasis each contribute to variable penetrance and severity of monogenic metabolic conditions; integrating ESM1b scores, PRS, and interaction effects could improve clinical prognosis for carriers. Music:Enjoy the music based on this article at the end of the episode. Article title:Investigating the sources of variable impact of pathogenic variants in monogenic metabolic conditions Journal:Nature Communications DOI:10.1038/s41467-025-60339-7 Reference:https://doi.org/10.1038/s41467-025-60339-7 License:This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/ Support:Base by Base – Stripe donations: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00 Official website https://basebybase.com On PaperCast Base by Base you'll discover the latest in genomics, functional genomics, structural genomics, and proteomics. Episode link: https://basebybase.com/episodes/variable-impact-pathogenic-variants-monogenic-metabolic QC:This episode was checked against the original article PDF and publication metadata for the episode release published on 2025-07-25. QC Scope:- article metadata and core scientific claims from the narration- excludes analogies, intro/outro, and music- transcript coverage: Audited portions of the transcript that discuss ESM1b variant pathogenicity scores, PRS carrier modification of phenotypes, marginal epistasis with FAME, replication in biobanks, and translational implications, plus limitations. Excluded non-scientific intro language and sponsor-like lines.- transcript topics: ESM1b variant pathogenicity scoring; Variant effect heterogeneity across monogenic genes; Polygenic risk scores and carrier phenotypes; Marginal epistasis and FAME method; Biobank-scale data sources and replication; Clinical implications and limitations QC Summary:- factual score: 10/10- metadata score: 10/10- supported core claims: 6- claims flagged for review: 0- metadata checks passed: 4- metadata issues found: 0 Metadata Audited:- article_doi- article_title- article_journal- license Factual Items Audited:- Three genetic contributors to penetrance and disease severity: heterogeneous variant effects, additive polygenic background, and marginal epistasis.- ESM1b scores predict mean phenotype and distinguish GOF vs LOF variants in several monogenic genes.- PRS modulates carrier phenotype; noncarriers in PRS tails can exhibit more extreme phenotypes than pathogenic carriers...