March 18, 2013
23andMe Discovers Genetic Associations For Myopia
Crowd sourcing for science.
Mountain View, Calif. – March 14, 2013 – In the largest ever genome-wide association study on myopia, 23andMe, the leading personal genetics company, identified 20 new genetic associations for myopia, or nearsightedness. The company also replicated two known associations in the study, which was specific to individuals of European ancestry. The study included an analysis of genetic data and survey responses from more than 50,000 23andMe customers and demonstrates that the genetic basis of myopia is complex and affected by multiple genes.
I think it is great that people are paying to get themselves genetically tested, filling in some online forms about their physical attributes, and thereby enabling original discoveries about human DNA. Crowd sourcing could do much more to enable biomedically useful discoveries about human health.
Myopia is the most common eye disorder worldwide. In the United States, an estimated 30 to 40 percent of the adult population is nearsighted. Myopia is a refractive error that results primarily from increased axial length of the eye. The increased physical length of the eye relative to optical length causes images to be focused in front of the retina, resulting in blurred distance vision.
The study, titled "Genome-Wide Analysis Points to Roles for Extracellular Matrix Remodeling, the Visual Cycle, and Neuronal Development in Myopia" was published on February 28, 2013 in PLOS Genetics, an open-access, peer-reviewed journal.
As the genetic test technology advances and generates more genetic data per test run the amount of information available for studies such as this one will explode. The flow of new genetic testing and sequencing results is going to rise by more orders of magnitude.
Clicking thru from the 23andMe site to the Illumina site (23andMe uses Illumina gene chips for testing) I found it interesting that these chips also detect copy number variations. So the chips can detect when a person has variations in the number of copies of genes. This is an important form of genetic variation.
Randall Parker, 2013 March 18 10:09 PM
IVF clinics are already screening embryos for some genetic problems. I can well imagine that as our understanding increases they'll screen embryos for a whole host of problems and maybe even eliminate some permanently. My only concern is jumping the gun and screening for certain genes before they fully understand how they work. For example, some genes that are linked to certain diseases actually help protect people from other diseaeses. So weven bad genes aren't always all bad. What if the genes linked to myopia also help protect people from macular degeneration and cataracts? Probably not but you never know.
It is more likely that the genes for myopia also play some role in increasing intelligence. There are a number of studies that show a correlation (the best one as I recall involved use of the Israeli Defence Forces as a study population). At one time I believed this was a case where intelligence led to myopia via excessive reading early in life, but I've seen later and more convincing hypotheses that suggest that the mechanism is hypertrophy of a variety of structures in the eye and forehead region. Basically, front-to-back expansion of your braincase also can have the unfortunate side effect of making your eyeballs a little too long.
Anyway, your point is well taken. Make sure you have a pretty good idea of *all* the uses a gene is put to before you choose it, or mess with it. In the case of myopia and intelligence, I bet the ongoing Chinese research into genetic variants tied to high intelligence will turn up some of the same candidates as this myopia research.
This is bogus. Its well-known that myopia is caused by doing too much close up work (reading, etc.) during childhood.
It's easy to see how someone might think too much reading causes myopia. After all, a bookworm who sits around reading all the time is more likely to need glasses than someone who spends a lot of time outdoors playing. But the most recent research suggests the actual cause is spending too much time indoors. Sunlight helps regulate eye growth.
I've read complaints by Eskimos that near sightedness has increased among those who eat a western diet.
I've heard about the eskimos, too. I've read that myopia was almost nonexistent among the previous generations but afflicts a majority of their kids. That suggests an environmental factor. But it doesn't mean there's not a genetic factor that predisposes them to higher rates under certain environmental conditions. I suppose there could be a dietary link. There's no law saying everyone's myopia has to be caused by the same thing. OTOH I'm skeptical of anecdotal evidence. As with the belief myopia was caused by reading, it could just mean their diets changed about the same time they started staying indoors more. You also have to consider that eskimos live at much higher latitudes where sunlight is less intense. Staying indoors might affect them more strongly since they're already getting weaker sunlight.
Yeah, "staying indoors". That would go along with spending less time freezing off body parts while hunting seal and whale.