“A Combined Analysis of Genetically Correlated Traits Identifies 107 Loci Associated With Intelligence”, W. David Hill, Gail Davies, A. M. McIntosh, C. R. Gale, I. J. Deary2017-07-07 (, ; backlinks; similar)⁠:

Intelligence, or general cognitive function, is phenotypically and genetically correlated with many traits, including many physical and mental health variables. Both education and household income are strongly genetically correlated with intelligence, at rg =0.73 and rg =0.70 respectively. This allowed us to use a novel approach, Multi-Trait Analysis of Genome-wide association studies (MTAG; Turley et al 2017), to combine two large genome-wide association studies (GWASs) of education and household income to increase power in the largest GWAS on intelligence so far (Sniekers et al 2017).

This study had 4 goals: firstly, to facilitate the discovery of new genetic loci associated with intelligence; secondly, to add to our understanding of the biology of intelligence differences; thirdly, to examine whether combining genetically correlated traits in this way produces results consistent with the primary phenotype of intelligence; and, finally, to test how well this new meta-analytic data sample on intelligence predict phenotypic intelligence variance in an independent sample.

We apply MTAG to 3 large GWAS: Sniekers et al 2017 on intelligence, Okbay et al 2016 on Educational attainment, and Hill et al 2016 on household income. By combining these 3 samples our functional sample size increased from 78,308 participants to 147,194. We found 107 independent loci associated with intelligence, implicating 233 genes, using both SNP-based and gene-based GWAS. We find evidence that neurogenesis may explain some of the biological differences in intelligence as well as genes expressed in the synapse and those involved in the regulation of the nervous system.

We show that the results of our combined analysis demonstrate the same pattern of genetic correlations as a single measure/the simple measure of intelligence, providing support for the meta-analysis of these genetically-related phenotypes. We find that our MTAG meta-analysis of intelligence shows similar genetic correlations to 26 other phenotypes when compared with a GWAS consisting solely of cognitive tests.

Finally, using an independent sample of 6,844 individuals we were able to predict 7% of intelligence using SNP data alone.