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domenica 2 giugno 2013

Varianti geniche associate al successo negli studi


Three Smart Genes
05/30/2013, Rachael Moeller Gorman
A new GWAS has found three genetic variants associated with educational achievement. How big are the effects? Find out.

In a massive genome-wide association study (GWAS) of 126,559 individuals, researchers have identified three single nucleotide polymorphisms (SNPs) associated with the amount of education a person achieves

In a massive genome-wide association study (GWAS) of 126,559 individuals, researchers have identified three single nucleotide polymorphisms (SNPs) associated with the amount of education a person achieves, with each allele accounting for about 1 month of schooling. This sample size is far larger than that of any previous study examining a social science trait.
Such research inevitably conjures up scenarios of genotyping people for educational potential at birth, and the discrimination and stigma that could follow.
But those fears are unwarranted right now, said Daniel Benjamin, associate professor at Cornell University and co-author of the paper published today in Science that reported those results (1). “We would never be able to predict enough to predict any one individual’s level of educational attainment with any accuracy. But for the purposes of doing studies in social science, this work could be really useful.

Social science GWASs that look for genetic variation associated with behavioral traits like subjective well-being, trust, and risk aversion, are a new breed. So far, the largest of these studies has included 20,000 people, and none have found SNPs that are significantly and robustly associated with any behavioral traits.
“Several of us independently came to the realization that we would need very large samples in order to do gene discovery for social science in an effective way,“ said Benjamin. In February 2011, he founded the Social Science Genetic Association Consortium with two colleagues—David Cesarini, and Philipp Koellinger—to organize workshops and to bring together a wide network of scientists to uncover the biological pathways underpinning human behavior.

Educational attainment, a complex behavioral trait, became their first project. They created a detailed analysis plan that collaborators at each of the 42 cohort sites ran on their existing genetic data (educational attainment is often a background question). The results were sent back to the consortium; three different meta-analysts at three different facilities across the globe ran further analyses.
Out of 2 million SNPs, the consortium found one significant needle-in-a haystack locus that correlated with years of schooling—rs9320913—and two for college completion —rs11584700 and rs4851266. They then replicated the test in 12 additional cohorts. They found that the rs9320913 SNP accounts for 0.02% of the variation across people in their educational attainment, or, about 1 month of schooling. The strongest college SNP, rs11584700, corresponds to a 1.8 percentage-point difference per allele in the frequency of completing college. Nearby genes have previously been associated with cognition, central nervous system, and health.
“I am quite confident that the effect is real,” said Benjamin. “Statistically speaking, since we found it in a sample of 100,000 people and it replicated in a sample of 25,000, it’s extremely unlikely to not be real.”
Compared to complex physical traits, the effect is tiny: the effect of the most significant SNP is 20 times smaller than SNPs for complex physical traits like height and BMI.
“But that’s actually one of the important messages of the paper,” said Benjamin. “It tells you, for one thing, that if personality and cognitive function have effect sizes in the same range as education does, then it was hopeless to have done GWAS studies with 20,000 people.”
But as for broad social policy in response to this study? “Any practical response—genetic or environmental, individual or policy-level—to this or similar research would be extremely premature,” the consortium writes.

References
1. Social Science Genetic Association Consortium. 2013. GWAS of 126,559 individuals identifies genetic variants associated with educational attainment. Science. [Online 30 May 2013]



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