Introduction
Hopefully this website will help you become more informed about founder effect and Ellis van Creveld syndrome. This website has been made by John Mikucki and Nicholas Tippins for Mrs. Kons G1 Biology.
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Introduction to Genetic Drift Genetic drift is changes in the frequencies of alleles in a population that occur by chance, rather than because of natural selection. It can occur when a small part of a population moves to a new locale (founder's effect) or when a population is reduced to a small size because of some environmental change (bottleneck effect). The founder effect is the change in allelic frequency when a new colony is formed by a very small number of individuals from a larger population. Unlike the parent population, the founding population has certain alleles in higher frequency . This is because it is completely random which genes (individuals) make up the founders causing some of the genes of the new society are disproportionately frequent in the resulting population.
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Ellis van Creveld Syndrome
Ellis van Creveld Syndrome is an inherited disorder of bone growth that results in very short stature (dwarfism). It is inherited in an autosomal recessive pattern carried on chromosome 4. People with this condition typically have particularly short forearms and lower legs; a narrow chest with short ribs, extra fingers and toes; malformed fingernails and toenails and dental abnormalities. An affected individual will pass the affected allele to all offspring and depending on the recessive/dominant nature of the other parent the offspring may or may not exhibit the traits in their phenotype. To get the disease, an offspring must inherit the diseased recessive variant of Chromosome 4 from each of their parents. Ellis van Creveld syndrome normally occurs in 1 in 60,000 to 200,000 newborns. The syndrome has had enormous prevalence in Lancaster County, Pennsylvania; home to the Old Order Amish
In other counties where 10% of the population is Amish, they account for about 50% of difficult-to-treat genetic disorders.
This is the problem faced in Lancaster County where Amish, Mennonites, and other Anabaptist suffer from devastating genetic defects like Creveld Syndrome.
In other counties where 10% of the population is Amish, they account for about 50% of difficult-to-treat genetic disorders.
This is the problem faced in Lancaster County where Amish, Mennonites, and other Anabaptist suffer from devastating genetic defects like Creveld Syndrome.
Explaining the prevalence of Ellis van Creveld in Lancaster County
Amish and other Anabaptist communities originated with a small group of Low-German immigrants who developed their own religious sect with strict rules on interactions with the outside world. This restricted the Amish gene pool to a small selection of genetic variants represented by the original Amish. This meant that the founder effect dictated a higher rate of genetic deformities. The syndrome has been traced to an Old Amish family that settled in Pennsylvania in 1744, the origin of this particular syndrome originates from Samuel King and his wife. Their 12 children intermarried within the limited gene pool of the Amish, resulting in an enormously greater prevalence of Van Crevelds Syndrome than the national average. Amish families produce large amounts of offspring to facilitate agricultural labor this has given more opportunity for inheriting recessive alleles. Amish communities until recently have rejected the tenements of modern medicine which made identifying threatening genes and syndromes more difficult. Anabaptists have strict rules about outside contact and the vast majority of Amish will marry into their own community and there is no influx of new population besides reproduction of the original Amish families. If on occasion the Amish marry outside their faith it is likely with an offshoot like Mennonites which account for the slightly milder rate of the syndrome in those communities. These factors contribute to an enormous prevalence of numerous genetic syndromes among the Old Order Amish which serves as an extreme example of Genetic Drift and the Founder Effect.
Works Cited
“Ellis-Van Creveld Syndrome.” U.S. National Library of Medicine, National Institutes
of Health, 21 Mar. 2017, ghr.nlm.nih.gov/condition/ellis-van-creveld- syndrome. Accessed 26 Mar. 2017. “Genetic Drift and the Founder Effect.” PBS, Public Broadcasting Service, 2001, www.pbs.org/wgbh/evolution/library/06/3/l_063_03.html. Accessed 26 Mar. 2017. “Untitled Document.” Untitled Document, www.ontrack-media.net/gateway/biology/g_bm3l3rs2.html. Accessed 26 Mar. 2017. |