15 April 2010

Understanding the Massive Complexity of Inheritance

"We know in the human genome there are 20,000 genes, but I can't ask someone to point out to me which genes account for most of the variation in human height, for example, because we just don't know," Kruglyak said. "The underlying goal of what we are trying to do is both understand how complicated these patterns are and try to come up with some concrete examples where we can take some traits and nail down most of the variations, as opposed to only finding a small percentage." _SD
Deciphering Genetic Complexity

Simple genetic traits such as eye and hair colour are relatively easy to understand, and trace through generations. More complex traits such as intelligence and the capacity to postpone gratification in order to achieve a greater reward, have a pattern of inheritance that is less well understood. A recently published (in Nature) Princeton study may point the way to better understanding how complex but critically important traits such as intelligence and executive function are transmitted via the genes.
"One of the important insights gained from research enabled by the sequencing of the human genome is that, rather than being obvious, the connections between genes and most traits are very complicated," Kruglyak said. "Our results show, however, that it is possible to identify many of the factors underlying complex traits using straightforward techniques."

The Princeton team's finding could help illuminate the answers to the current difficulties inherent in tying traits to genes, known as the "missing heritability problem," Kruglyak said.
There are some cases, he said, where scientists have identified mutations in single genes that produce a specific trait, such as a susceptibility to cystic fibrosis or Huntington's disease.

In most cases, however, scientists believe that large numbers of genes working in concert produce trait variation. Some genes play a major role while others are more "quiet" but still are important. Scientists want to know all of the genes involved in producing a given complex trait, but they have not been able to find these groupings, leading to the "missing" problem.

... "In many cases, the effects of genes are so small that detecting them is extremely difficult," said Ian Ehrenreich, a postdoctoral research fellow who is the first author on the Nature paper. "Under conventional methods, we just don't have the power to identify many of these genes. We knew we had to find a different way."... _SD

In other genetics research, scientists at Uppsala University have developed better ways of identifying genetic variation in active genes.

Researchers at Virginia Tech and the Virginia Bioinformatics Institute are developing computer tools to help find small genes that are too easily missed by conventional gene sequencing of microbes.

Huxley's "Brave New World" is coming to reality with the increasing use of "gene swaps" in human eggs -- to prevent the perpetuation of genetic diseases.

The ability to compare genetic sequences for both normal and cancer cells in the same patients can open the door to a better understanding of the vulnerabilities of specific cancers.

Genes are information that is transmitted and instantiated in complex ways. They determine much of who you are and what you can become. The deep and honest study of gene expression is one of the keys to a better future for everyone.

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