A recent study from the Queen Mary University of London and elsewhere identified a new protein linked to age-related macular degeneration (AMD).
It showed much higher levels of a protein called factor H-related protein 4 (FHR-4) in the blood of AMD patients.
Further tests, using eye tissue donated for medical research, showed the presence of the FHR-4 protein within the macula—the specific region of the eye affected by the disease.
The results open up new routes for early diagnosis, by measuring FHR-4 levels in the blood, and suggest therapies targeting this protein could provide promising future treatment options for the disease.
The findings could offer new hope for the diagnosis and treatment of the disease, which affects over 1.5 million people in the UK alone.
The study is published in Nature Communications. One author of the study is Dr. Valentina Cipriani.
FHR-4 regulates the complement system, part of the immune system, which plays a critical role in inflammation and the body’s defense against infection.
Previous studies have linked the complement system to AMD showing that genetically inherited faults in key complement proteins are strong risk factors for the condition.
In this study, the researchers used a genetic technique, known as a genome-wide association study, to identify specific changes in the genome related to the increased levels of FHR-4 found in AMD patients.
They found higher blood FHR-4 levels were associated with changes to genes that code for proteins belonging to the factor H family, which clustered together within a specific region of the genome.
The identified genetic changes also overlapped with genetic variants first found to increase the risk of AMD over 20 years ago.
Together, the findings suggest that inherited genetic changes can lead to higher blood FHR-4 levels, which results in uncontrolled activation of the complement system within the eye and drives disease.
There are two main types of AMD – ‘wet’ AMD and ‘dry’ AMD. Whilst some treatment options exist for ‘wet’ AMD, there is currently no available treatment for ‘dry’ AMD.
The team says this study really is a step-change in the understanding of how complement activation drives this major blinding disease.
It is a tangible step closer to identifying a group of potential therapeutic targets to treat this debilitating disease.
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