Age-related macular degeneration (AMD) is one of the leading causes of blindness, and there may now be new hope for treating or even preventing it. An international team of scientists has identified a specific protein that may be the cause of the disorder.

The study included scientists from Queen Mary University of London, the University of Manchester, Cardiff University, and Radboud University Medical Center in The Netherlands. It involved analyzing blood samples obtained from 484 AMD patients, along with samples from 522 age-matched people who did not have the disease.

It was found that the AMD group had significantly higher levels of a substance known as factor H-related protein 4 (FHR-4) within their blood. Additionally, when eyes donated from deceased AMD patients were examined, they were likewise found to have FHR-4 in the macula.

FHR-4 regulates a part of the immune system called the complement system. That system in turn plays a key role in inflammation, and in the body's defence against infection. Importantly, previous studies have suggested that overactivity of the complement system may lead to AMD.

Genetic analysis of the AMD group members further indicated that their higher FHR-4 levels were associated with changes to genes that code for proteins belonging to the factor H family. These same changes had previously been linked to an increased risk of AMD, over 20 years ago.

"This study really is a step-change in our understanding of how complement activation drives this major blinding disease," says the University of Manchester's Prof. Simon Clark. "Up until now, the role played by FHR proteins in disease has only ever been inferred. But now we show a direct link and, more excitingly, become a tangible step closer to identifying a group of potential therapeutic targets to treat this debilitating disease."

A paper on the research was recently published in the journal Nature Communications.

Sources: Queen Mary University of London, University of Manchester