One of the toughest things about studying genetics is the way people from different family and genetic backgrounds constantly come together and have children whose genetic make-up becomes progressively more heterogeneous. Historically, certain groups like the Amish have maintained a distance from mainstream population. Their closed community was started by just a few people (founder effect) and throughout 200 years of inbreeding with few new genes introduced, some rare genetic diseases surfaced.
It sounds bad to say that researchers have taken advantage of these isolated populations, but their clear genetic lineage has made it easier to discover new genes. Dr. Holmes Morton and his wife, Caroline, who set-up the first research clinic in the Amish community of Pennsylvania claims to have identified about 150 genes involved in causing diseases including sudden infant death syndrome. Instead of resenting the intrusion of outsiders and their lab equipment, the Amish have welcomed the Holmses and support their research by raising money from the sales of quilts, furniture, and baked goods.
Dr. Alan Shuldiner (in whose lab I worked as a graduate student) has been studying diabetes, heart disease, and longevity in the Amish with a $10 million grant from the National Institutes of Health. He’s been collecting blood samples hoping to uncover the genes involved in common chronic diseases.
Once genes have been identified in these special populations, the next step would be to study them in the rest of us. Some genes might have a strong effect in populations where people share many common genes due to founder effect, but the genes’ effects might be diluted in the general population. Also bear in mind that genes work in concert with each other and with the environment to cause disease.
The question is, are groups like the Amish living a lifestyle that is too different from ours? Are they representative of the rest of us, esp. those of us belonging to a different race? If, for instance, the Amish diet is healthier and they get more exercise, genes that increase the risk of cardiovascular disease in the presence of high cholesterol wouldn’t cause disease in the Amish.
At this stage of the genome revolution, any kind of data helps to fill out the larger picture of how genes work to cause or prevent disease. Studying the Amish or Ashkenazi Jewish populations may make it easier to find the genes that are the “loudest.” More subtle effects probably won’t be detected until we have more in vitro information on the intricacies of molecular and cellular biology.
The Boston Globe, July 4, 2005