Age-related macular degeneration (AMD) has been one of the leading causes of blindness on the planet for decades, severely impacting many people"s quality of life.
However, the thousands of sufferers in the UK and the rest of the world may now have a ray of hope in the form of a study which has identified one of the causes of the conditions.
Research conducted by experts at Tufts Medical Center, Tufts University School of Medicine and Brigham and Women"s Hospital and published in the journal Nature Genetics suggests that a genetic mutation is responsible for AMD.
Experts had previously identified several relatively common genetic variants which together predict a person"s increased risk for AMD, though a significant number of people without the disease also have these variants.
Now, however, investigators have been able to clearly show a specific rare mutation called CFH R1210C, which predicts a very high risk of disease and is extremely uncommon among those who do not have the disease.
First author, Dr Soumya Raychaudhuri, a researcher in the Divisions of Genetics and Rheumatology at Brigham and Women"s Hospital, said that although it is a rare variant, it is highly related to familial disease and earlier age of onset.
"Our paper shows that there is a genetic variant that confers high risk of the development of AMD; this finding not only clearly links CFH gene dysfunction to disease, but also might help to identify people who need to be screened more closely," she explained.
Before publication, it was known that genetic variation within the CFH gene influenced people"s risk of AMD in individuals, so in this study, researchers conducted sequencing and genotyping of CFH in 2,423 AMD cases and 1,122 controls.
They identified a rare, high-risk mutation resulting in an arginine to cysteine substitution in the CFH protein, which is associated with loss of function of the CFH protein.
Its discovery suggests that loss of CFH function can drive AMD risk, explained senior author Dr Johanna Seddon, professor of ophthalmology at Tufts University School of Medicine and director of the Ophthalmic Epidemiology and Genetics Service at Tufts Medical Center.
She added that it was associated with advanced AMD and visual loss, while many of the patients also had numerous drusen, which are the early hallmarks of AMD.
"The discovery of this rare but penetrant variant strongly associated with disease also points the way to developing new and effective treatments for high risk individuals," the expert added.
by Martin Burns