Reading material 2 - QA for the paper on polygenic prediction of educational attainment.pdf

Finally polygenic predictions only hold for as long

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more) predictive for individuals in some environments than for individuals in others. Finally, polygenic predictions only hold for as long the environment in which they were developed remains substantially the same: if the laws or pedagogy underlying a population’s educational system changes substantially, then so, too, might the polygenic score. Just as eyeglasses allow those genetically predisposed to poor vision to have nearly perfect vision, innovations in education (say, an innovation that makes education irresistibly engaging, thus mitigating the risk to those with genetic variants associated with lower ability to pay attention or maintain self-control) might result in those with lower polygenic scores now achieving just as much education, on average, as those with higher polygenic scores (see also FAQs 3.2 and 3.3). As sample sizes for GWAS continue to grow, it will likely be possible to construct a polygenic score for educational attainment whose predictive power comes closer to 20% of the variance in educational attainment across individuals (Rietveld et al. 2013). Even this level of predictive power would pale in comparison to some other scientific predictors. For example, professional weather forecasts correctly predict about 95% of the variation in day-to-day temperatures. Weather forecasters are therefore vastly more accurate forecasters than social science geneticists will ever be. Note: The results of SSGAC studies have sometimes been used in other projects to predict individual traits. We recognize that returning individual genomic “results” can be a fun way to engage people in research and other projects and to stoke their interest in, and educate them about, genomics. But it is important that participants/users understand that these individual results are not meaningful predictions and should be regarded essentially as entertainment. Failure to make this point clear risks sowing confusion and undermining trust in genetics research.
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20 3.5 Can your polygenic score be used for research studies in non-European-ancestry populations? Only in a limited way. As a practical matter, it is possible to calculate a polygenic score for any individual for whom genome-wide data is available, but the polygenic score will be much less “predictive” (see FAQ 1.4) in non-European-ancestry populations. Our study was conducted only using samples of individuals of European ancestries (see Appendix 1). The set of SNPs that are associated with educational attainment in people of European ancestries is unlikely to overlap perfectly with the set of SNPs associated with EA in people of non-European ancestries. And even if a given SNP is associated in both ancestry groups, the effect size—in other words, the strength of the association—will almost surely differ. This is primarily because linkage disequilibrium (LD) patterns (i.e., the correlation structure of the genome) vary by ancestry. This means that some variant may be associated with educational attainment because the variant is in LD (i.e., correlated) with a variant elsewhere in the genome that causally affects education (see FAQ 1.3). If the strength of the correlation is greater in one
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