polygenic mutation-selection balance

Date created: 2022-06-09

It’s the phenomenon that explains why genetic variation associated with mental disorders persists despite lowered evoluationary fitness.

Given that mental disorders are caused by many (hundreds or thousands) of genetic variations, and that only a sufficient amount of them results in a disorder, there is a balance between the chance of mutation (one SNP changing to a risk allele) and selection (lower evolutionary fitness).


  • Keller, M., & Miller, G. (2006). Resolving the paradox of common, harmful, heritable mental disorders: Which evolutionary genetic models work best? Behavioral and Brain Sciences, 29(4), 385-404. doi:10.1017/S0140525X06009095