NHGRI logo
Chromosome

Founder Effect

updated: May 24, 2022

Definition

A founder effect, as related to genetics, refers to the reduction in genomic variability that occurs when a small group of individuals becomes separated from a larger population. Over time, the resulting new subpopulation will have genotypes and physical traits resembling the initial small, separated group, and these may be very different from the original larger population. A founder effect can also explain why certain inherited diseases are found more frequently in some limited population groups. In some cases, a founder effect can play a role in the emergence of new species.



Narration

Founder effect is a phenomenon in the work that we do that refers to the migration of a small group of people from a larger population to go settle in another environment. And they carry along with them a subset of genetic information that existed in the larger population. And because of that, carrying the subset, they actually reduce the amount of genetic variation that exists within a new population now. And as a result of that, they may emphasize certain phenotypes or certain genes, and all this may be deemphasized. So a founder effect can sometimes impact a population in such a way that they may have less of a particular type of gene or more of a particular type of gene. And it can change what we call phenotype, which is the things that we look at like your height, you know, your weight, or having a particular disease or not having a particular disease. So in effect that is what founder effect is.