Rare Genetic Variants Drive Human Extremes Rather Than Polygenic Effects
Researchers analyzing 74 human traits found that individuals at the extreme ends of distributions—such as exceptionally high or low cholesterol, blood glucose, or body weight—may carry rare genetic variants with stronger effects rather than thousands of common variants with minimal impact. The study examined data from the UK Biobank and All of Us Research Program to determine whether genetic architecture differs for people at trait extremes. These findings could enable clinicians to provide more tailored preventive care based on individuals' specific genetic risk profiles.
The research examined 74 different measurable human characteristics using genetic information from two major research initiatives: the UK Biobank and the All of Us Research Program. The scientific team employed two distinct statistical methods to evaluate whether people displaying extreme trait values—unusually high cholesterol or body weight, for instance—inherited a fundamentally different set of genetic influences compared to the general population.
The study's theoretical foundation rests on evolutionary principles. Genetic variations that strongly push traits toward extremes may occasionally harm survival or reproduction rates, causing natural selection to maintain them at low frequencies across generations. This mechanism could explain why uncommon variants with substantial biological effects accumulate among individuals at distribution extremes, while widespread variants with modest effects dominate the general population.
These findings could reshape clinical approaches to preventive medicine and disease management. If physicians can identify patients whose extreme traits stem from rare high-impact variants rather than common polygenic influences, they may tailor interventions and screening protocols accordingly. This personalized approach could improve disease risk assessment for conditions like cardiovascular disease and diabetes, potentially allowing earlier or more targeted treatments. The discovery may particularly benefit individuals with unusual measurements who currently receive generic risk guidance.