for National Geographic News
The genetic makeup of the human race is much more varied than previously believed, new research shows.
Scientists say that surprisingly many large chunks of human DNA differ among individuals and ethnic groups.
The research also suggests that humans have less DNA in common with chimpanzees, our closest living relative, than is widely supposed.
The new findings, based on several studies, will have dramatic implications for research into deadly diseases, the researchers add.
In the lead study, reported tomorrow in the journal Nature, scientists created the first map of the human genome that shows that large segments of DNA are missing or duplicated between normal, healthy people.
Known as copy number variants (CNVs), some of these altered DNA sequences can be responsible for increased susceptibility to cancers and many other diseases, the study team says.
The new map provides a much clearer picture of human genetic variation, says geneticist and co-researcher Charles Lee of the Harvard Medical School in Boston, Massachusetts.
"This evidence is showing that we are more genetically unique from one another—we all have individualized genomes," he said.
The team analyzed the DNA of 270 people with ancestry in Europe, Africa, and Asia. (Get an overview of human genetics.)
More than 1,400 CNVs were detected, covering 12 percent of the human genome—the complete set of chromosomes, present in almost every human cell, that contains a person's genetic code.
Until now only relatively small amounts of genetic difference between people had been identified.
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