Twenty-four genes linked to short-sightedness have been identified by an international consortium of scientists. The Consortium of Refractive Error and Myopia (CREAM) also confirmed the association of two previously reported genes. The researchers analysed genetic data collected from 32 studies of over 45,000 people of European and Asian heritage.
'We already knew that myopia – or short-sightedness – tends to run in families, but until now we knew little about the genetic causes', said lead author Professor Chris Hammond from the Department of Twin Research and Genetic Epidemiology at King's College London. 'This study reveals for the first time a group of new genes that are associated with myopia and that carriers of some of these genes have a ten-fold increased risk of developing the condition'.
About 30 percent of Western people and up to 80 percent of Asian people are affected by myopia, reports the study published in the journal Nature Genetics. Myopia is caused during childhood development when the eye grows too long. If this occurs light entering the eye focuses in front of, rather than on, the light-detecting layer of cells called the retina. The image seen consequently appears blurred.
Although myopia is more prevalent in Asian populations, the genetic variants found to associate with the condition were not significantly different between the European and Asian populations analysed. The genes implicated include those involved in signalling between nerve cells, eye development and structure. Some of the genetic variants identified carried a particularly high risk, such that carriers were found to be ten times more likely to become short-sighted.
Myopia can increase the risk of several eye conditions, including detachment of the retina, glaucoma and macular degeneration. There is no cure at present and myopia can only be corrected with glasses, contact lenses or surgery. 'But now we understand more about the genetic triggers for the condition we can begin to explore other ways to correct it or prevent progression', Professor Hammond explained.
Environmental factors are already known to play a role in increasing the risk of developing myopia. 'There is some data to suggest that short-sightedness is becoming more common in children in the UK', remarked Professor Hammond to the Independent. 'It’s very likely that sitting indoors on your computer games is not as good as being outdoors looking at the blue yonder'.
The consortium will carry out further research to see how environmental factors interact with the genes and determine the risk of developing myopia. Eye health campaigns manager at the Royal National Institute of Blind People, Clara Eaglen, told the Daily Mail: 'Any new understanding of the cause of short-sightedness will help us get closer to finding treatments that will prevent the condition progressing'.