Scientists have identified a key protein linked to age-related macular-degeneration, a leading cause of blindness, that they say could help in early diagnosis and efforts to design novel treatment strategies.

The researchers in the Netherlands and the UK have found that patients with age-related macular degeneration have significantly higher than usual levels of a protein called FHR-4 in their blood and in the macula, the affected region of the eye.

Age-related macular degeneration, the leading cause of loss of vision in people aged above 60 years, occurs through damage to the macula — a central region of the retina. Besides ageing, other factors that appear to increase the risk include smoking, high cholesterol and high blood pressure.

Although some treatment options exist and ophthalmologists underscore the importance of early diagnosis and intervention, the disease is considered debilitating and vision-threatening.

Scientists suspect that genetic factors also play a role in macular degeneration. The FHR-4 protein the scientists have identified helps regulate a component of the immune system that plays a key role in inflammation and the body’s defence against infections.

“By unveiling FHR-4 as a novel molecular player for age-related macular degeneration, our study was able to dissect further genetic disease predisposition at the protein level,” said Valentina Cipriani, a researcher and study team member at the Radboud University Medical Centre in the Netherlands.

Cipriani and her colleagues published their findings in the journal Nature Communications on Friday.

Until now, researchers had only suspected a role for FHR-4.

“Now we show a direct link and, more excitingly, come a tangible step closer to identifying a group of potential therapeutic targets to treat this debilitating disease,” Simon Clark, a team member at the University of Manchester said in a media release.

Paul Bishop, an ophthalmologist at the University of Manchester, said the research while improving the biological mechanisms of age-related macular degeneration also provides a way to predict the risk of the disease by measuring blood levels of FHR-4.

The finding, he said, also opens a possible route to treatment by reducing blood levels of FHR-4 to restore the immune system function in the eyes.