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New DNA map shows more gene variations

SAN FRANCISCO -- Researchers have plotted a new human DNA map that could help identify people who are genetically vulnerable to diseases such as AIDS.

The map includes the replication and absence of large DNA segments found in healthy people. The researchers found the DNA segments, called copy number variants, or CNVs, cover 12 percent of the human genome, more than previously thought, according to a study to be published today in the journal Nature .

The study throws new light on genetic diversity among individuals. The absence and duplication of larger DNA segments, the CNVs, has the biggest impact on the flow of hereditary information, and not the millions of basic building blocks of DNA as previously thought. The segments affect a gene's protein production and make an individual susceptible to disease.

The new map "can be combined with preexisting data to provide a much more comprehensive understanding of human genetic variation," Charles Lee, a Brigham and Women's Hospital pathologist and part of the international research group, said in a statement. It has "immediate implications to disease association studies, genetic diagnostic testing, and cancer research."

That may take time because a complete map of the segments covering different races is necessary to understand the impact of each segment, Duke University's Kevin V. Shianna and Huntington F. Willard wrote in a peer review of the study. The review will also be published in Nature.

It took the researchers two years to identify more than 1,400 segments. They studied genetic codes from 270 individuals from four populations with ancestry in Europe, Africa, or Asia.

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