The Human Genome Project mapped the billions of letters that make up the human genetic code. Scientists later refined the map by looking for single variations called single nucleotide polymorphisms (SNP), in the arrangement of those letters which make individuals unique.

The CNV map gives researchers a different way to look for genes linked to diseases by identifying gains, losses and alterations in the genome.

"Copy number variation is complex. There are different types," said Dr. Matthew Hurles, of the Wellcome Trust Sanger Institute in England.

"In addition to deletions and duplications, there are more complex forms where a gene can be present in one individual in multiple copies in a tandem array," he told the news conference.

He added that resistance to infection by HIV, which causes AIDS, is determined in part by multiple copies of the gene CCL3L1, which cannot be seen on an SNP map.

NEW TOOLS

The scientists, whose findings are reported in the journals Nature, Nature Genetics and Genome Research, compiled the CNV map by comparing DNA from 270 healthy people in China, Japan, Nigeria and the United States.

The consortium identified 1,447 different CNVs that covered about 12 percent of the human genome. About 285 of them are associated with diseases. CNV duplication is linked to schizophrenia, psoriasis, coronary heart disease and congenital cataracts.

"With these new tools, we and our clinical colleagues are able to find previously undetectable deletions or duplications of the genome in a patient. The CNV map now allows us to identify which of these changes are unique to the disease," said Dr. Nigel Carter, of the Wellcome Trust Sanger Institute.

The scientists have also developed a database called DECIPHER that will enable researchers around the world to use the Internet to submit information on patients with CNV details. The information will be mapped on to the human genome in the public browser.

"This important work will help identify genetic causes of many diseases," said Dr. Mark Walport, director of the Wellcome Trust, in a statement.

Copyright © 2006 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.

Obesity may improve survival rate of kidney cancer

Last Updated: 2006-11-22 15:38:38 -0400 (Reuters Health)

By David Douglas

NEW YORK (Reuters Health) - Although obesity increases the risk of developing kidney cancer, patients with greater body mass index (BMI) seem to have less aggressive disease, according to researchers. BMI, the ratio of weight to height, is a common means of estimating whether someone is overweight or underweight.

Although obesity appears to double the risk of developing kidney cancer, also referred to as renal cell carcinoma, there is some evidence that those with a greater BMI at the time of diagnosis may have a better outcome, Dr. Alexander S. Parker of the Mayo Clinic, Jacksonville, Florida and colleagues report in the medical journal Urology.

To investigate further, the researchers studied data from 970 patients who underwent surgery for clear cell renal cell carcinoma, the most common type of kidney cancer.

Less aggressive tumors were more likely to be found in patients who were considered to be overweight (having a BMI of 25 to 29), or obese (having a BMI 30 or greater), compared with patients who were underweight or normal weight.

The 5-year survival rate from kidney cancer was 82 percent for obese patients, 77 percent for overweight patients and 62 percent for normal-weight patients.

Compared with normal-weight patients, the risk of death from clear cell renal cell carcinoma was reduced by 52 percent for obese patients and by 36 percent for overweight patients. However, the researchers point out that BMI adds little in the way of prognostic information beyond that afforded by available methods.

Nevertheless, Parker told Reuters Health that the relationship between less aggressive tumors and higher BMI "needs to be further evaluated to determine if this is due to increased screening and early detection among obese individuals, or if obese patients really do develop less aggressive tumors."

"If the latter is true," he concluded, "this would have the potential to tell us exciting new things about how renal clear cell carcinomas develop and how best to treat them."

SOURCE: Urology, October 2006.

Copyright © 2006 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.