The discovery of a new "blindness" gene could help doctors save thousands of people's sight, UK scientists hope.
A second 'culprit' gene was found
A team at Leeds University located the faulty DNA code behind a rare form of retinal disease that runs in families.
In turn, this should enable doctors to understand and treat more common forms of blindness affected by the growth of abnormal eye blood vessels, they say.
Their research, which is ongoing, is published in the American Journal of Human Genetics.
They looked at people who had inherited a condition called familial exudative vitreoretinopathy (FEVR).
In this disease the vessels of the eye do not grow in the normal way, which can lead to blindness depending on how severe the problem is.
Scientists had already pinpointed one gene on chromosome 11 that appeared to cause FEVR.
However, Dr Carmel Toomes and colleagues at Leeds University noted that this gene did not explain all cases of FEVR.
When they looked closer they found a second gene on the same chromosome that was linked to the condition.
Although this is a very rare disease, the implications of the findings are far reaching, say the researchers.
Cures in sight
They hope it will lead to earlier detection and intervention and possibly new treatments for things such as diabetic retinopathy and age-related macular degeneration, which are the leading causes of blindness in the western world.
Dr Toomes said: "If we can understand the molecules that cause blood vessel development by looking at FEVR that might help us piece together the pathway for normal blood vessel growth and abnormal blood vessel growth."
She said they had been given a grant to investigate whether similar genes might also be implicated in blindness in premature babies.
Mr Andrew Webster, consultant ophthalmologist at Moorfields Hospital in London, said: "This is an important discovery in that it has identified the underlying cause of a blinding disorder.
"These findings enable doctors to better understand the nature of this rare condition.
"Furthermore, the identification of these two genes also helps us to understand the processes that take place early in life that are responsible for the development of a normal, functioning retina."
Nick Astbury, president of the Royal College of Ophthalmologists, said: "This research could lead to improved genetic tests, diagnostics, management and counselling for people with FEVR, and may contribute to decreasing the risk of becoming blind by allowing early detection of the condition in those at risk.
"Eventually, this may help identify new treatments for other vascular eye diseases, such as diabetic retinopathy."