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November 23, 2006

New human gene map shows unexpected differences

Human DNA can have up to 10% variation based upon the number of duplicated sequences. The finding that questions the idea that everyone on Earth is 99.9 percent identical genetically.

Instead of showing single variations in human DNA that make people unique, the map looks at differences in duplications and deletions of large DNA segments known as copy number variants or CNVs, which can help explain why some people are susceptible to illnesses such as AIDS and others are not.

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, including 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.

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