By improving our understanding of vascular development, the breakthrough could also shed light on other diseases including tumour formation and arthritis.

Carmel Toomes, member of the Leeds vision research group, said the work could lead to early diagnosis of diseases affecting the light-sensitive part of the eye which cause the majority of cases of blindness and visual disability in the UK.

Thanks to her gene discovery, Dr Toomes has begun a Royal Society research fellowship which will enable her to continue the research for at least another five years.

The effects of blindness can be devastating, she said. It is very frightening to imagine how your life would change if you were to lose your sight, but for many this is a reality. By the time we retire, one in 50 of us will have a significant defect of vision and after retirement the incidence rises sharply.

Although retinal disease is mostly untreatable, and sight can rarely be restored once vision loss has occurred, it can sometimes be prevented if a patient is diagnosed early enough.

Dr Toomes is using genetics to understand the disease. While there are many different causes for the various types of retinal blindness, the cellular processes involved are often similar.

The group is studying rare inherited forms of retinal disease in order to understand the more common forms of blindness affected by the growth of abnormal blood vessels in diabetic retinopathy and ageing-macular dystrophy “ the leading causes of blindness in the western world. The research should lead to the development of new treatments for these conditions.

The discovery of the new blindness gene was reported in the American Journal of Human Genetics.

leeds.ac/

Sir Walter adds: "Cancer susceptibility is most probably due to the cumulative effect of many individually infrequent genetic variants, rather than a modest effect of one or more common variants. This could help explain why it has been difficult to identify specific genes that confer genetic susceptibility to cancer, and also to conditions as varied as schizophrenia and Alzheimer's disease."

Dr Lesley Walker, Director of Cancer Information at Cancer Research UK, says: "Introduction of a national screening programme for bowel cancer was announced last week. People over 60 will from April 2006 be screened using a test known as the faecal occult blood test (FOBT) followed by colonoscopy to detect early cancers and polyps. However, scientists will continue investigating a range of screening techniques in order to save as many lives as possible.

"Finding the genetic mutations that cause around 20 per cent of bowel cancers will be an important advance in our understanding of the disease, and could also help in efforts to prevent the disease in those at high risk."

cancerresearchuk