Genetic marker discovered for intraocular pressure – the most important risk factor for glaucoma

Research led by a Moorfields consultant and funded by the Wellcome Trust has identified a common genetic marker for elevated intraocular pressure – a major risk factor in the development and progressive worsening of glaucoma and of particular relevance as the only effective treatments for glaucoma work by lowering IOP.  The discovery could eventually enable the more effective identification of people at risk of raised IOP, as well as the development of new treatments for glaucoma, which affects 60 million people worldwide.

The findings of the five-year Genome Wide Association Study (GWAS) study were published in the leading journal Human Molecular Genetics on July 11.  The £2 million study was led by Moorfields consultant and ophthalmic surgeon Ananth Viswanathan, based on work by an international group of scientists and ophthalmologists based in 37 centres*. 

 “The identification of the marker represents a significant milestone in the understanding of the genetic basis of glaucoma, the commonest cause of irreversible blindness worldwide,” says Mr Viswanathan. 

 “Our study identified that 99% of people will have the variant on at least one strand of their DNA, while 77 % will have it on both.  Using knowledge from epidemiology of the effect of IOP on glaucoma risk and risk of worsening, we estimated that each copy of the variant increases the risk of developing glaucoma by 8%, and in established glaucoma each copy gives an extra 6% likelihood of significant visual loss. 

 “The gene implicated is involved in a metabolic process known as vesicle handling.  We know this is how the aqueous humour leaves the eye so the finding sheds light on the biological processes involved and may lead to new drug targets. Another group looking at glaucoma (not specifically IOP) also found genes elsewhere on the genome involved in vesicle handling, so an interesting picture is emerging.”