A recent genome-wide association study published in Nature Genetics purports to show a link between two novel genetic variants and the morphology of the brain and head, specifically the volume of the skull and the size of the hippocampus, says Genomes Unzipped's Luke Jostins. However, while the study was "very well carried out" and the associations look "to be well established," the study has flaws, Jostins adds. "The vast majority of this paper follows the laid down protocols for a high-quality genome-wide association study," he says. "But beyond the GWAS portion of the study, these standards of evidence are loosened significantly."
In a subset of subjects, the researchers looked at IQ, finding a weak association between HMGA2 and IQ, and, further, HMGA may be associated with general body size, Jostins says. "There is no point in keeping rigorous standards of evidence if you are going to start breaking them during follow-up, and it does the field a disservice if your genome-wide-significant brain size association ends up alongside your nominally-significant IQ association in a news report," Jostins adds.