Amish populations in Lancaster County, Pennsylvania have high rates of a rare form of dwarfism. The recessive allele that codes for this disorder is found in 1 of 14 individuals in this Amish population, in contrast to 1 in 1,000 in the general population. In Ohio, an Amish population suffers with higher than normal rates of cystic fibrosis and a host of other genetic diseases so rare that some have not yet been named. What factors have caused such severe genetic problems in these two communities?
What will be an ideal response?
These Amish groups are insular populations, each descended from a small group of ancestors that migrated to the United States. The genes the founding groups carried with them was dictated by chance alone. Due to their religious beliefs, the Amish have married among themselves. Rare, recessive genes have become more common through the generations as related members marry and increase the odds of being carriers of the disorders. These severe genetic problems are a combination of the founder effect and nonrandom mating.
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