ScienceDaily - New Genes Linked to Brain Size, Intelligence

ScienceDaily (Apr. 15, 2012) — In the world’s largest brain study to date, a team of more than 200 scientists from 100 institutions worldwide collaborated to map the human genes that boost or sabotage the brain’s resistance to a variety of mental illnesses and Alzheimer’s disease. Published April 15 in the advance online edition of Nature Genetics, the study also uncovers new genes that may explain individual differences in brain size and intelligence.

In an intriguing twist, Project ENIGMA investigators also discovered genes that explain individual differences in intelligence. They found that a variant in a gene called HMGA2 affected brain size as well as a person’s intelligence.
DNA is comprised of four bases: A, C, T and G. People whose HMGA2 gene held a letter “C” instead of “T” on that location of the gene possessed larger brains and scored more highly on standardized IQ tests.
“This is a really exciting discovery: that a single letter change leads to a bigger brain,” said Thompson. “We found fairly unequivocal proof supporting a genetic link to brain function and intelligence. For the first time, we have watertight evidence of how these genes affect the brain. This supplies us with new leads on how to mediate their impact.”