Determinants of penetrance and variable expressivity in monogenic metabolic conditions across 77,184 exomes

Abstract

Hundreds of thousands of genetic variants have been reported to cause severe monogenic diseases, but the probability that a variant carrier will develop the disease (termed penetrance) is unknown for virtually all of them. Additionally, the clinical utility of common polygenetic variation remains uncertain. Using exome sequencing from 77,184 adult individuals (38,618 multi-ancestral individuals from a type 2 diabetes case-control study and 38,566 participants from the UK Biobank, for whom genotype array data were also available), we applied clinical standard-of-care gene variant curation for eight monogenic metabolic conditions. Rare variants causing monogenic diabetes and dyslipidemias displayed effect sizes significantly larger than the top 1% of the corresponding polygenic scores. Nevertheless, penetrance estimates for monogenic variant carriers averaged below 60% in both studies for all conditions except monogenic diabetes. We assessed additional epidemiologic and genetic factors contributing to risk prediction, demonstrating that inclusion of common polygenic variation significantly improved biomarker estimation for two monogenic dyslipidemias.

A model and test for coordinated polygenic epistasis in complex traits

“…Another example is the omnigenic model, which suggests that traits are determined by a few trait-specific "core" genes that are modified by many nonspecific "peripheral" genes (31,32), implying coordinated epistasis (CE) between the SNPs contributing to "core" and "peripheral" genes. Monogenic disorders with polygenic modifiers are another instance of structured epistasis, where the expressivity and penetrance of mutations in a core gene are modified by many variants distributed among the genome (33)(34)(35).…”