Predicting Glaucoma Before It Starts: How Close Are We to Genetic Risk Scores That Actually Change Patient Outcomes?

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Predicting Glaucoma Before It Starts: How Close Are We to Genetic Risk Scores That Actually Change Patient Outcomes?Glaucoma – a group of diseases damaging the optic nerve – is the leading cause of irreversible blindness worldwide (). Globally it affects tens of millions of people, a number expected to grow with aging populations (). The most common form, primary open-angle glaucoma (POAG), is often silent in its early stages. In fact, studies estimate roughly half of glaucoma cases remain undiagnosed until vision loss begins () (). This is unfortunate because early detection matters: standard treatments (eye drops, laser or surgery to lower intraocular pressure) can effectively slow or halt progression when started early () (). Glaucoma’s insidious onset but treatable nature makes it an ideal candidate for predictive screening. Genetics offers one promising avenue. POAG is highly heritable – first-degree relatives have about a 9-fold higher risk than average! (). Estimates put genetic heritability of POAG at roughly 70–80% () (). These facts suggest that a person’s DNA contains valuable clues to their future glaucoma risk.Early clinics have long tested for rare single-gene mutations (e.g. MYOC, OPTN) in families with juvenile or early-onset glaucoma (). But such Mendelian variants account for only a small minority of cases () (). Most glaucoma is polygenic: influenced by many common genetic variants each contributing a small risk. Over the past decade, large genome-wide association studies (GWAS) have identified hundreds of genomic loci linked to glaucoma and related traits () (). For example, a 2023 study (N > 600,000 Europeans plus multi-ancestry cohorts) found 263 independent risk loci, and further expanded this to 312 loci by including diverse populations (). These discoveries go beyond intraocular pressure genes – they include factors involved in optic nerve structure and even immune pathways. Such rich genetic data raise the question: can we summarize an individual’s inherited risk into a single score that meaningfully predicts future glaucoma?Polygenic Risk Scores for GlaucomaA polygenic risk score (PRS) does exactly that: it adds up the small effects of thousands of common genetic variants into one number (). In simple terms, a PRS estimates how a person’s DNA influences their chance of developing a disease. Importantly, a PRS is not a diagnosis – it is a probabilistic risk estimate (). For glaucoma, researchers have now built PRS using well-established risk variants and tested them in large cohorts. The results are encouraging: people in the highest percentiles of the glaucoma PRS are at substantially higher risk of the disease than those with average scores () (). For example, one study in an Australian population used hundreds of variants related to eye pressure and optic nerve shape. Individuals in the top PRS decile had about 5–6 times the odds of developing glaucoma compared to those in the bottom decile (). Another comprehensive PRS (using thousands of SNPs for glaucoma and its related traits) showed an even larger effect: the top decile had roughly 10–20× the risk of glaucoma relative to the bottom dec