By Helen Briggs BBC News science reporter

The map will relate genetic variation to particular diseases

One thousand people are to have their genomes mapped in a major effort to understand how genes influence disease.

To date, only a handful of humans have had their genes analysed in this way, including scientists Craig Venter and James Watson, and anonymous volunteers.

Teams in the UK, US and China say the project will create the most useful catalogue ever of genetic variation.

Any two humans are genetically more than 99% identical: variations can explain why some get certain diseases.

Current catalogues of human genetic variation have led to the discovery of more than 100 regions of the genome - the complete package of genetic material in a living thing - that could explain susceptibilities to diseases such as diabetes, breast cancer and rheumatoid arthritis.

We can do 100 times as much sequence today as before for the same amount of money Dr Richard Durbin

The international research consortium behind the 1,000 Genomes Project aims to build on this work by providing a much more detailed map of disease-related differences for use by all scientists.

"The dream of people working in the field would be to have a picture of all the places in our DNA sequence where there are differences between people, and how these fit together when they are inherited," Dr Richard Durbin of the Wellcome Trust Sanger Institute, who is co-chair of the consortium, told BBC News.

"We can do 100 times as much sequence today as before for the same amount of money," he explained.

"That allows us to think about sequencing 1,000 people in order to see directly all those differences between people and to provide a foundation for future human genetics."

Knowledge gap

The map is designed to fill in the gaps in our knowledge about how genetic variation is related to disease.

The 1,000 Genome Project Cost: $30m to $50m Will read 6 trillion DNA building blocks Includes populations from Africa, Asia, America and Europe

Most current research focuses on rare genetic changes in the human code that run in families and cause severe inherited diseases such as cystic fibrosis, or common differences that appear to underpin a host of major diseases.

"Between these two types of genetic variants - very rare and fairly common - we have a significant gap in our knowledge," said Dr David Altshuler, the other co-chair of the consortium.

"The 1,000 Genomes Project is designed to fill that gap, which we anticipate will contain many important variants that are relevant to human health and disease."

Anonymous samples

The work to sequence (read) human DNA will be carried out by the Sanger Institute in Cambridge, Beijing Genomics Institute in Shenzhen, and the National Human Genome Research Institute (NHGRI), which is part of the US National Institutes of Health (NIH).

They will use samples from volunteer donors who gave informed consent for their DNA to be analysed and placed in public databases.

Only a handful of people in the world have had their genomes mapped by science: the public Human Genome effort used bits of DNA from 12 unnamed volunteers, while private efforts in the US have unravelled the genetic code of US scientist Craig Venter and Nobel prize winner James Watson.