A very large genome-wide association study (GWAS) of brain and intracranial size has just been published in Nature Genetics. The study looked at brain scans and genetic information from over 20,000 individuals, and discovered two new genetic variants that affect brain and head morphology, one which affects the volume of the skull, and one of which affects the size of the hippocampus.
The main study is very well carried out, and the two associations look to me to be well established. However, there are a few little things about the paper that, when combined with some biased reporting in the press, that have been bothering me. Firstly, the main result that has been reported in the news is that the study found an “IQ gene”, but this was only a very small follow-on in the study, and the evidence underlying it is relatively weak (certainly not the “Best evidence yet that a single gene can affect IQ”, as reported by New Scientist). Secondly, the authors use a misleading reporting of statistics to hide the fact that one of their association could easily be cause by an (already well known) association to general body size.