Davide Piffer, Figshare, April 24, 2015
A review of published intelligence GWA studies was carried out.The average frequency (polygenic score) of nine alleles positively associated with intelligence is strongly correlated to country IQ (r= 0.91). Factor analysis of allele frequencies produced a factor with a similar correlation to IQ (0.86).The majority of alleles (7/9) loaded positively on this factor. Allele frequencies varied by continent in a way that matched the average group-level of phenotypic intelligence. Average allele frequencies for intelligence GWAS hits had higher inter-population variability than background expectations or height GWAS hits. This may suggest stronger selection for intelligence than human height. Random sets of SNPs and Fst distances were employed to deal with the issue of spatial autocorrelation, due to population structure. GWAS hits were much stronger predictors of IQ than random SNPs. Regressing IQ on Fst distances did not significantly alter the results but it confirmed that, whilst evolutionarily neutral (genome-wide) genetic distances are indeed related to IQ differences between populations, the GWAS hits frequencies predict the latter above and beyond the former.
[Editor’s Note: The full paper is available at the original article link below.]