An international team of researchers have found a clue to one of the most important causes of blindness, which they hope could eventually lead to a cure. Age-related macular degeneration affects 500,000 people in the UK and is not curable.
The study in the journal Nature found an enzyme recognized as DICER1 that stops functioning, resulting in the illness. UK experts said it had the possible to be an important breakthrough.
The macula is a part of the eye which sits in the centre of the retina and is accountable for the fine detail at the centre of the field of vision. As the disease progresses that central vision declines, making reading, driving and recognizing people difficult. It affects one in 50 people over 50 and one in five people over 85.
The precise cause is unknown, but risk factors include smoking, high blood pressure and having relatives with the condition.
The researchers noticed the enzyme DICER1 was less active in the retina of people with the more common "dry form" of the sickness and when they turned off the gene which makes the enzyme in mice, then the animal's retina cells were damaged. It was then discovered that DICER1 is essential for destroying small pieces of genetic material called Alu RNA.
Without DICER1, the Alu RNA accumulates with toxic penalty leading to the death of the retina. Professor Jayakrishna Ambati, from the University of Kentucky, told the BBC: "This work opens many new doors of investigate.
"First, we need to identify various classes of molecules that can either add to DICER1 levels or block Alu RNA so that these can be evaluating in clinical trials. "Second, we need to understand more about the biological processes that lead to reduction in DICER1 levels and the precise basis of the Alu RNA transcripts."
Professor Ian Grierson, school of clinical sciences at the University of Liverpool, said: "This is a great piece of science which provides another jigsaw piece which we need to put together with other findings. "It was done in an animal model which is a long way from the patient; the breakthrough is we've got another player."
Professor Mike Cheetham, head of molecular and cellular neuroscience at UCL, said: "It's a potentially very important get through which gives insight into this dry form of the disease.”It could provide new pathways to therapy, but the findings need to be validated by other researchers."