Genes, Brain Volume, and IQ

ENIGMA researchers reported that a genetic sequence, located within the HMGA2 gene on chromosome 12, was linked with intracranial volume. Meaning, how large your brain can get inside the outer limits of your bony skull. At this spot, every C-allele variant was linked to not only lower intracranial (inside your skull) volume, but also to lower IQ scores on the Multidimensional Aptitude Battery, a measure of intelligence. (DNA is made up of four bases—A, C, T and G.) Lead ENIGMA researcher Paul Thompson, a neurologist at the University of California, Los Angeles, School of Medicine, was quoted as saying: "This is a really exciting discovery: that a single letter change leads to a bigger brain.”