To map regions of the brain to specific genes, researchers at the University of California – San Diego did genome-wide association studies (GWAS) of the regional cortical surface area and thickness of 39,898 adults and 9,136 children. That is, they scanned complete sets of DNA (genomes), looking for genetic variations. They were especially interested in variations that might be associated with a problem like autism, epilepsy, or dementia.

By and large, construction of the human brain is determined by heredity, though factors like environmental exposures also play a role, particularly during sensitive periods of neurodevelopment during childhood. Large-scale MRI and genetic datasets have increasingly illuminated the common genetic variants that help build the human cerebral cortex — the outer, layered sheet of wrinkled tissue associated with humans’ highest mental capabilities, such as language, memory, perception, awareness and consciousness.

University of California – San Diego, “Genetically informed atlases reveal new landscapes in brain structure” at ScienceDaily (February 7, 2022) The paper requires payment or a subscription.

But what about variations, especially the ones that cause problems? Describing their work, the researchers, led by Carolina Makowski, noted that the use of genetically defined atlases of the brain allowed them to uncover 440 genome-wide significant loci in the study group and 800 in a combined meta-analysis later — “the largest number of genetic variants to date associated with the size and thickness of the cortex.”

Intriguingly, many of the genes that these loci map to are also associated with neurodevelopmental disorders, such as autism, epilepsy and intellectual disability, and dementia,” said [radiologist Chi-Hua] Chen.

University of California – San Diego, “Genetically informed atlases reveal new landscapes in brain structure” at ScienceDaily (February 7, 2022) The paper requires payment or a subscription.

Chen, who led the work, also offered,

”To some extent, the molecular machinery for normal brain development and disorders overlaps, which could reflect a continuous spectrum of genetic effects on normal brain structural variation to aberrant neurodevelopment. One possible mechanism is that certain genetic compositions cause abnormal brain development, which leads to neurodevelopmental disorders. The loci we discovered can be used by researchers for further mechanistic studies of how genes impact the brain and diseases.”

University of California – San Diego, “Genetically informed atlases reveal new landscapes in brain structure” at ScienceDaily (February 7, 2022) The paper requires payment or a subscription.

The more we know about exactly how some difficult disorders originate, the more opportunities we have to head them off.

You may also wish to read: Detailed brain mapping outlines what we can — and can’t — know. Your brain, fully mapped, would take up a good part of the internet. And then it would just change again. Living things, even comparatively simple ones, cannot be entirely comprehended by simple measurements.