In the search for genetic insights into a variety of human conditions, evolutionary biologists often focus their research efforts on mutated or dysfunctional genes, assuming that a change or loss of function in the resulting protein will cause or contribute to a certain condition. However, research conducted by Anna Di Rienzo, Ph.D., Associate Professor, Human Genetics, and her research team provides the first genetic evidence suggesting that the opposite scenario may also be true. The findings, published in the December 2004 issue of the American Journal of Human Genetics, suggest that the normal gene, not the more common mutation, is responsible for sodium retention and its link to increased rates of hypertension in certain ethnic groups.

"Historically, we have looked for mutations or alterations in the genes behind certain disorders such as cystic fibrosis," explains Di Rienzo. "Now, however, we are beginning to explore common variants that perhaps were necessary when humans lived in a sustenance economy but have become a liability in a world of plenty. In our modern economy, it may be that the undamaged genes are the ones that predispose certain individuals to a certain condition."

Di Rienzo and her team focused their work on a gene called CYP3A5, part of the cytochrome P450 gene family, which aid the body in breaking down and eliminating a variety of elements. CYP3A5 works in the kidney to metabolize cortisol and in turn retain salt; however, a mutated version of this gene, CYP3A5*3, creates a nonfunctional protein.

"We looked at this gene in 1,064 individuals from 52 populations around the world and found that the mutation was least common in the native populations of sub-Saharan Africa closest to the equator," Di Rienzo continues. "In contrast, the occurrence rate of the mutation increased incrementally according to latitude, and we found the highest rate of occurrence in the isolated Basque population in the Pyrenees mountains."

"Our findings suggest a firm correlation between a population's distance from the equator and the occurrence of CYP3A5*3," says Di Rienzo. "This discovery is a remarkable example of the pressures of natural selection, and I believe it will open up new avenues for researchers in their approach to a variety of human conditions."

FOREFRONT
The Division of the Biological Sciences is proud to announce the appointment of two new Professors and Chairmen for the Departments of Psychiatry and Medicine...

Comer Children's Hospital Dedication
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DISCOVERIES
In the search for genetic insights into a variety of human conditions, evolutionary biologists often focus their research efforts on mutated or dysfunctional genes, assuming that a change or loss of function in the resulting protein...

DEVELOPMENT
Development is on pace to meet a goal of $65 million in FY2005. Midway through the fiscal year, approximately $30 million has been contributed, and the Spark Discovery campaign has raised more than $420 million...

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ACCOLADES
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