Harvard researchers map new form of genetic diversity

A new map of human genetic diversity provides a powerful tool for understanding how each person is unique.

Created by researchers at Harvard Medical School, Brigham and Women’s Hospital, and other institutions around the world, the map focuses on the number of copies of large segments of DNA present in each individual. Though humans normally have two copies of their DNA, researchers found that some people have three, four, five, or more copies of certain DNA segments, while others have just one copy or are even missing them entirely.

Working as part of an international consortium, the group identified 1,447 DNA segments that vary from the normal number of two copies. Included in those DNA segments, called copy number variants (CNVs), are the DNA that make up 3,000 genes, including 285 genes known to be associated with disease.

Researchers believe that variations in the number of copies of these disease genes may explain disease susceptibility and why, for example, one person develops cataracts in old age while another doesn’t. Among those 285 are genes linked to AIDS, schizophrenia, inflammatory bowel disease, lupus, and arterial disease.

The work, detailed in the Nov. 23 edition of the journal Nature, involved researchers from 13 institutions. Principal investigators included Charles Lee, assistant professor of pathology at Harvard Medical School and a cytogeneticist at Brigham and Women’s Hospital; Stephen Scherer of the Hospital for Sick Children in Toronto; Matthew Hurles, Nigel Carter, and Chris Tyler-Smith of the Wellcome Trust Sanger Institute; Hiroyuki Aburatani of the University of Tokyo; and Keith Jones of Affymetrix Inc.