Individuals And Populations Differ In Gene Activity Levels, Not Just Genes

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Individuals And Populations Differ In Gene Activity Levels, Not Just

Genes

http://www.sciencedaily.com/releases/2007/03/070302082421.htm

Much like how a person's genetic code differs from other

individuals, the level at which those genes are activated in the

body differs from one person to another, scientists have learned.

And though some of those differences in gene activity are seen

between different populations -- Asians versus Europeans, for

instance -- more of those variations are due to individual-level

factors, further obscuring the biological meaning of " race. "

The findings could also have major implications for medical

research, as differing levels of gene activity may affect one's

susceptibility to developing a disease or one's response to a

particular drug. The research was conducted at the University of

Washington, and was led by Akey, assistant professor of

genome sciences, and Storey, associate professor of genome

sciences and of biostatistics. Their findings appear in the March

issue of the American Journal of Human Genetics.

" This is exactly what makes drug development so difficult, or why

it's so hard to pinpoint an exact cause for a particular disease, "

said Akey. " People have so much variation both in their genetic

information and in how those genes are activated and regulated. We

need to have a much better understanding of human genetic and gene-

expression variation in order to better treat complex diseases and

develop more effective drugs. "

The researchers examined data on thousands of genes from 16 people

of European and African ancestry, cataloging the variations between

those individuals. They studied each person's levels of gene

expression, which measures how much a particular gene is activated

during the process of translating DNA into a substance called RNA,

and from that into basic proteins. The more a gene is expressed, the

more " messenger " RNA is produced, leading to formation of more

proteins corresponding to that gene. Those proteins are the building

blocks that make up living cells and tissue.

" The difference between genetic information and gene expression is

like the difference between computer hardware, which are the genes

themselves, and computer software, which tells the computer what to

do on the hardware, " explained Storey. " We looked at what's

happening inside the body, beyond what's hard-wired into the genes. "

Scientists have known for many years about genetic variation, in

which individual letters in the genetic code change between

individuals and between different populations. However, this study

is one of the first to look at the variation in gene activity

between individuals and populations.

The researchers found many differences in gene-expression levels,

and that about 17 percent of those differences were due to

population-level differences. The vast majority of the gene-

expression variation was due to random differences between

individuals, and was not tied to ancestral population or

biological " race. "

" It's important to remember that differences between population

groups are much less abundant than those you would see if you just

compared two randomly selected individuals, " said Storey. " This

means that populations have a lot more similarities than differences

when it comes to gene expression. "

Their findings may help us better understand how human populations

are structured and interrelated, and could also help explain

evolutionary development of humans from our ancient ancestors to

present day. The research may also help us understand why some

people are more susceptible than others to complex genetic diseases.