SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.
Myopia, or nearsightedness, affects more than a quarter of the U.S. population. Doing a lot of “close-up work,” including reading, may bring on the condition or make it worse (as a society’s literacy rates rise, so does the rate of myopia), but there is a considerable genetic component too.
Myopia usually develops because the eyeball grows to be too long. In animal models of myopia, changes in eye tissue associated with reduced levels of a growth factor called TGF-β1 have been shown to be responsible for this elongation. Two recent studies tried to connect TGF-β1 to myopia in humans by looking at genetic variations in the gene that encodes the protein, but the results were conflicting.
The authors of a new study, published online today in the Archives of Ophthalmology, sought to clarify the role of the TGF-β1 gene in human myopia by analyzing several genetic variations in 300 nearsighted Chinese people and 300 with normal vision. The nearsighted people had a particularly severe form of myopia known as high myopia (usually defined as -6.00 diopters or worse, but this study used -8.00 diopters).
The researchers found that one SNP in the TGF-β1 gene in particular was associated with high myopia. Each A at rs4803455 decreased the odds of developing the condition by 0.67 times.
(23andMe customers can check their data at rs4803455 using the Browse Raw Data feature.)
The authors say that their results solidify the TGF-β1 gene as a player in myopia, but the question of how rs4803455 affects the gene or the risk for the condition remains unanswered. Analysis of the TGF-β1 gene sequence showed that the different versions of rs4803455 might affect the amount of protein made from the gene, but further laboratory experiments will be needed to explore this possibility. Alternatively, rs4803455 may be just a signpost pointing the way to a nearby genetic variant that truly affects the risk of myopia.