Glaucoma is among the main causes of irreversible blindness worldwide and it is estimated that it will affect about 76 million people by 2020.
To date there is no single definitive biomarker for glaucoma and diagnosis involves the evaluation of the clinical features of the disease, in which the characterisation of the optic nerve plays the crucial role. Primary open-angle glaucoma is asymptomatic in its early stages, which is why about half of all cases go undiagnosed, even in the most developed countries.
Early diagnosis, on the other hand, is crucial because, although there is no curative cure for glaucoma, the process of optic nerve degeneration can be countered through early diagnosis and appropriate treatment. The late diagnosis represents, on the contrary, an important risk factor for blindness.
Hence the need for strategies to identify individuals at high risk of developing the disease.
A study conducted by Australian researchers and recently published in the prestigious journal Nature Genetics identified 107 genes related to an individual's increased risk of developing glaucoma.
The researchers characterised photographs of the optic nerves of 67,040 subjects from the UK Biobank and carried out a whole-genome association study (Genome-Wide Association Study, GWAS) on optic nerve morphology, using other endophenotypes such as intraocular pressure (IOP) and vertical cup/disc ratio. With this state-of-the-art 'multitraits' approach, the researchers were able to first identify new risk loci for glaucoma, then generate a polygenic risk (PRS) for glaucoma that can identify individuals most at risk of developing the disease.
The PRS, developed in the study, has been shown to be predictive of: increased risk of advanced glaucoma; disease status significantly beyond traditional risk factors; need for early diagnosis; elevated levels of absolute risk in persons carrying high-penetrance variants for glaucoma; increased likelihood of disease progression in early stages; and increased likelihood of incisional glaucoma surgery in the advanced stage of the disease.
The polygenic risk score for glaucomacreated by Australian researchers, showed a good predictive power in a wide range of clinical cohorts and its application could facilitate rational allocation of resources and timely treatment of high-risk patientswhile decreasing the costs of clinical monitoring of low-risk subjects.
Source:
Dr. Carmelo Chines
Direttore responsabile
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