Thursday, March 13, 2014
Polydactyly in the Amish Population
The Founder Effect is felt heavily in the Amish population with Ellis-van Creveld syndrome, which causes polydactyly. When the original small population of a community contains an unusually high amount of one gene, this gene is spread throughout the population as it increases, thus creating the Founder Effect. This occurs within the Amish, as the original founders contained genes for Ellis-van Creveld syndrome, and as the population grew within its small borders the gene was kept in close quarters and is therefore far more common than in average global populations. Ellis-van Creveld syndrome causes polydactyly, short ribs, disproportional short stature, short limbs, small trunk, dental anomalies, dystrophic nails, congenital cardiac disease, and genu valgum (knock-knees). These symptoms are detailed here. In short, a syndrome you do not want to have. In average populations, rare genes such as this are filtered out through a large proportion of dominant genes which override it. However, because of the small population size and occasional interbreeding of the Amish communities, Ellis-van Creveld syndrome has become common.