Scientists in Britain have identified 15 new genes responsible for common inherited diseases.
The medical researchers say the discovery could be a big step forward in the search for treatments.
200 scientists were involved in what was the biggest ever study on inherited diseases.
The study by the Wellcome Trust analysed DNA from the blood of 17,000 people to find genetic differences.
The research, which cost £9m, involved 50 leading research groups which analysed the DNA from 2,000 sufferers of each of seven conditions and 3,000 volunteers.
'Gene chips' were used to scan hundreds of thousands of DNA markers to find common genetic differences.
They found new genetic variants for depression, Crohn's disease, coronary heart disease, hypertension, rheumatoid arthritis and Type 1 and 2 diabetes.
Many of the genes identified were in parts of the genome not previously thought to be associated with disease.
It is hoped the research will pave the way for research into new treatments and genetic tests that will allow scientists to understand how disease happens and which people are most at risk.
Professor Peter Donnelly of the Wellcome Trust Case Control Consortium and professor at Oxford said they had learnt more in the last year than they had in 15 years.
