Genetic discovery has implications for cloning, cancer

NEW YORK (CNN) -- A newly discovered genetic process offers tantalizing clues for cancer researchers and reveals possible obstacles to cloning, scientists report.

Results show that despite the success of mapping the human genetic code -- the human genome -- it is only a first step in understanding how genes work.

Four articles in this week's Science magazine detail how genes in human DNA appear to be controlled by a sea of surrounding proteins that functions as a master switch.

Molecular geneticists call the newly discovered process the 'histone code' and say they are just beginning to translate it.

The articles describe methylation, a chemical process that acts as a trigger. Scientists have watched the common organic molecule methyl interact with the proteins surrounding DNA, and say the cell appears to use the process to switch blocks of genes on and off.

The discovery may be a new argument against human cloning. Even with the right cell and the right DNA, until scientists understand "this parallel rule book of genetics," they cannot clone without error, said researcher C. Davis Allis at the University of Virginia, who worked on the projects.

Surrounding DNA with the wrong histones could trigger tumors or developmental problems, he said.

The discovery also complicates the understanding of genetic disease, Allis said, because it means a faulty gene alone may not be to blame for a medical condition. The protein neighborhood that surrounds the gene may be at fault instead.

Learning how to manipulate the histone code is key, Allis said. "If we knew how to control which genes we want to turn on or off, we might be able to reduce disease risk," he said. "For example, we could turn off genes that promote tumor growth to help prevent cancer development, turn on other genes that suppress tumors."

The work was done in four labs by researchers at the University of Virginia, the National Institutes of Health, Cold Spring Harbor in New York, and Vienna, Austria.