by Krishna Ramanujan
(Medical Xpress)—As human population grows, disease-causing genetic mutations per individual increase, but each mutation is less harmful, when compared with a population that is not growing, says a Cornell study to be published in November in the journal Genetics.
The study also reports that natural selection has efficiently removed the most harmful genetic mutations, called very deleterious mutations, from the population and has removed a higher fraction of such mutations per generation.
The researchers used computer simulations to predict the role of natural selection on human genetic architecture in the face of rapid population rise. With advances in agriculture, public health, medicine and technology, human populations have soared in the last 500 years from around half-a-billion in 1500 A.D. to more than 7.1 billion today.
The findings have important implications for genetic and personalized medicine: For every disease-causing gene, there may be many slightly altered forms of that gene, called alleles, from one person to the next. This knowledge may point researchers to look for different alleles for the same disease.
"If you know that you have more deleterious variations in the population, then you know, on average, two people will likely have different variants" of the same disease-causing gene, said Elodie Gazave, the study's lead author and a postdoctoral researcher in plant breeding and genetics. Gazave is a former postdoctoral researcher in the lab of Alon Keinan, a senior author of the study and the Robert N. Noyce Assistant Professor in Life Science and Technology in the Department of Biological Statistics and Computational Biology.
These finding may provide insights for researchers searching for genes that cause disease. Though people have invested millions of dollars to explain diseases and their relationship to genes, progress has been slow, Gazave said. For example, 81 percent of schizophrenia cases are thought to have a genetic basis, and yet researchers have only identified a genetic source in 1 percent of those cases. Mostly, researchers use an associational method for identifying common variants of disease; they identify an allele that causes a disease and they look for that same allele in other people with the disease, but mostly they fail to locate it.
Based on the finding that there are more alleles for each gene, Gazave suggests it may serve better to develop a mapping method that looks for alleles on chromosomal regions known to house a disease-causing gene.
"If we know what we are looking for then we are maybe more likely to find it," Gazave said.
The most-asked question regarding such population genetics studies is whether people are becoming less healthy or fit based on the findings. The researchers measured fitness and found that the two main results – that there are more mutations, but each mutation is less deleterious – "exactly balance out," Gazave said.
"Explosive [population] growth affects a lot of things, but eventually the fitness is not affected," Gazave said.
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by Krishna Ramanujan
(Medical Xpress)—As human population grows, disease-causing genetic mutations per individual increase, but each mutation is less harmful, when compared with a population that is not growing, says a Cornell study to be published in November in the journal Genetics.
The study also reports that natural selection has efficiently removed the most harmful genetic mutations, called very deleterious mutations, from the population and has removed a higher fraction of such mutations per generation.
The researchers used computer simulations to predict the role of natural selection on human genetic architecture in the face of rapid population rise. With advances in agriculture, public health, medicine and technology, human populations have soared in the last 500 years from around half-a-billion in 1500 A.D. to more than 7.1 billion today.
The findings have important implications for genetic and personalized medicine: For every disease-causing gene, there may be many slightly altered forms of that gene, called alleles, from one person to the next. This knowledge may point researchers to look for different alleles for the same disease.
"If you know that you have more deleterious variations in the population, then you know, on average, two people will likely have different variants" of the same disease-causing gene, said Elodie Gazave, the study's lead author and a postdoctoral researcher in plant breeding and genetics. Gazave is a former postdoctoral researcher in the lab of Alon Keinan, a senior author of the study and the Robert N. Noyce Assistant Professor in Life Science and Technology in the Department of Biological Statistics and Computational Biology.
These finding may provide insights for researchers searching for genes that cause disease. Though people have invested millions of dollars to explain diseases and their relationship to genes, progress has been slow, Gazave said. For example, 81 percent of schizophrenia cases are thought to have a genetic basis, and yet researchers have only identified a genetic source in 1 percent of those cases. Mostly, researchers use an associational method for identifying common variants of disease; they identify an allele that causes a disease and they look for that same allele in other people with the disease, but mostly they fail to locate it.
Based on the finding that there are more alleles for each gene, Gazave suggests it may serve better to develop a mapping method that looks for alleles on chromosomal regions known to house a disease-causing gene.
"If we know what we are looking for then we are maybe more likely to find it," Gazave said.
The most-asked question regarding such population genetics studies is whether people are becoming less healthy or fit based on the findings. The researchers measured fitness and found that the two main results – that there are more mutations, but each mutation is less deleterious – "exactly balance out," Gazave said.
"Explosive [population] growth affects a lot of things, but eventually the fitness is not affected," Gazave said.
Explore further: Fate of new genes cannot be predicted
Medical Xpress on facebook
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As population exploded, more rare genes entered human genome
May 11, 2012
(Medical Xpress) -- As the Earth's human population has skyrocketed since the rise of agriculture some 10,000 years ago -- to 7 billion people from a few million -- so, too, has the number of rare genetic variants.
Fate of new genes cannot be predicted
Sep 13, 2013
New versions of genes, called alleles, can appear by mutation in populations. Even when these new alleles turn the individuals carrying them more fit to survive and reproduce, the most likely outcome is that ...
Digesting milk in Ethiopia: A case of multiple genetic adaptations
Aug 29, 2013
A genetic phenomenon that allows for the selection of multiple genetic mutations that all lead to a similar outcome—for instance the ability to digest milk—has been characterised for the first time in ...
Family studies suggest rare genetic mutations team up to cause schizophrenia
May 28, 2013
Using a novel method of analyzing genetic variations in families, researchers at Johns Hopkins have found that individually harmless genetic variations affecting related biochemical processes may team up to increase the risk ...
Genetic switches play big role in human evolution
Jun 12, 2013
(Phys.org) —A Cornell study offers further proof that the divergence of humans from chimpanzees some 4 million to 6 million years ago was profoundly influenced by mutations to DNA sequences that play roles ...
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30 minutes ago
When developing new drugs, monitoring cellular responses to candidate compounds is essential for assessing their efficacy and safety. Researchers from the RIKEN Center for Life Science Technologies report ...
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43 minutes ago
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Whole-exome sequencing IDs genetic cause in quarter of cases
3 hours ago
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They were mystery diseases that had stumped doctors for years—adults with strange symptoms and children with neurological problems, mental slowness or muscles too weak to let them stand. Now scientists say they were able ...
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The discovery of genetic differences affecting up to a third of the population could take the guesswork out of prescribing the correct dose of 25 percent of drugs currently on the market, researchers say.
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A groundbreaking study of nearly 2,300 extremely obese diabetes patients, led by the Translational Genomics Research Institute (TGen), has identified genes associated with unhealthy liver function.
User comments
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