World's largest catalogue of human genomic variation created

Scientists have created the world's largest catalogue of genomic differences among humans that will provide powerful clues to why some people are susceptible to various diseases.
While most differences in peoples' genomes - called variants - are harmless, some are beneficial, while others contribute to diseases and conditions, ranging from cognitive disabilities to susceptibilities to cancer, obesity, diabetes, heart disease and other disorders.
Understanding how genomic variants contribute to disease may help clinicians develop improved diagnostics and treatments, in addition to new methods of prevention.
An international team of researchers in the US, UK, China, Germany and Canada from the 1000 Genomes Project Consortium examined the genomes of 2,504 people from 26 populations across Africa, East and South Asia, Europe and the Americas.

In the study, researchers identified about 88 million sites in the human genome that vary among people, establishing a database available to researchers as a standard reference for how the genomic make-up of people varies in populations and around the world.
The catalogue more than doubles the number of known variant sites in the human genome, and can now be used in a wide range of studies of human biology and medicine, providing the basis for a new understanding of how inherited differences in DNA can contribute to disease risk and drug response.

Of the more than 88 million variable sites identified, about 12 million had common variants that were likely shared by many of the populations.

The study, published in the journal Nature, showed that the greatest genomic diversity is in African populations, consistent with evidence that humans originated in Africa and that migrations from Africa established other populations around the world.
"The 1000 Genomes Project was an ambitious, historically significant effort that has produced a valuable resource about human genomic variation," said Eric Green director of The National Human Genome Research Institute (NHGRI), part of the US National Institutes of Health.
"The latest data and insights add to a growing understanding of the patterns of variation in individuals' genomes, and provide a foundation for gaining greater insights into the genomics of human disease," Green said.

In a companion paper also published in Nature, scientists examined differences in the structure of the genome in the 2,504 samples.
They found nearly 69,000 differences, known as structural variants. These genomic differences, many of which affected genes, include deletions (loss of DNA), insertions (added DNA), and duplications (extra DNA copies).
The researchers created a map of eight classes of structural variants that potentially contribute to disease.