The largest-ever release of childhood cancer genome data has been announced by US researchers.

Scientists at the Washington University Paediatric Cancer Genome Project announced in the journal Nature Genetics that they have released hundreds of genome sequences mapping the DNA of 260 children with cancer.

By comparing cancer DNA with DNA from healthy cells in the same patient, the new data provides a detailed picture of the genetic changes causing the disease.

The amount of data released more than doubles the volume of whole genome data currently available worldwide.

The project at St Jude Children's Research Hospital is the world's largest effort to understand the genetic origins of childhood cancers.

This is the first time that a major privately funded human genome sequencing project has shared its data as soon as it becomes available.

Researchers at St Jude will analyse the genomic sequences to determine the differences between each child's healthy and cancerous cells.

This will help them to identify the genetic causes of some of the most deadly childhood cancers.

The three-year Paediatric Cancer Genome Project, which will cost an estimated £41.5 million, was launched in 2010.

It has already yielded important insights into aggressive childhood cancers of the retina, brain stem and blood.

The project is expected to sequence more than 1,200 genomes by the end of 2012. Its latest data release can be accessed for free via the European Genome-Phenome Archive.

Dr James Downing, project leader at St Jude, said: "By sharing the information even before we analyse it ourselves, we're hoping that other researchers can use this rich resource for insights into many other types of diseases in children and adults."

Josephine Querido, science information manager at Cancer Research UK, said: "Research unravelling the genetic secrets behind cancer is hugely important and will lead to new ways of diagnosing and treating the disease, keeping families together for longer in years to come.

"This study in childhood cancer is part of a global effort to catalogue the gene faults that drive many different cancers. Cancer Research UK recently launched two similar projects as part of the International Cancer Genome Consortium, looking for genetic mistakes in hundreds of prostate and oesophageal cancers."

Source: CRUK