Regarding the variety and anatomical granularity of brain structural phenotypes, our knowledge of the genetics of the human cerebral cortex is restricted. A recent study by the University of Cambridge used a genome-wide association meta-analysis to find 4,349 significant loci across the entire experiment for 13 structural and diffusion MRI-derived cortical characteristics.
This is the largest-ever study of the brain’s genetics, including some 36,000 brain scans. It has identified more than 4,000 genetic variants linked to brain structure.
There’s no doubt that the brain is a very complex organ. However, little is known about how our genetic makeup shapes brain development.
A group of researchers from the University of Cambridge‘s Autism Research Centre accessed the MRI scans of over 32,000 people from the UK Biobank cohort and over 4,000 children from the ABCD study to find out the answer to this issue. Using these scans, the researchers took several measurements of the cortex, the brain’s outermost layer. These included measures of the cortex’s volume, surface area, and folding.
They then connected these characteristics, assessed across the entire cortex and in 180 distinct cortical areas, to genetic information present throughout the genome. Over 4,000 genetic variations connected to brain anatomy were found by the team.
These discoveries have made it possible to validate and, in some cases, pinpoint the genetic relationships between various aspects of the brain.
One question that gathered scientists’ interest is if the same genes linked to how big the cortex is – measured as both volume and area – are also linked to how the cortex is folded. They discovered that several gene sets affect the folding and growth of the cortex by assessing these many aspects of the brain and relating them to genetics.
The team also looked into whether the same genes linked to cephalic disorders or clinical conditions where head sizes are significantly larger or lower than the general population overlap with genes linked to variation in brain size in the general population.
Dr. Richard Bethlehem, also from the Autism Research Centre and a co-lead of the study, said: “Many of the genes linked with differences in the brain sizes in the general population overlapped with genes implicated in cephalic conditions. However, we still do not know how exactly these genes lead to changes in brain size.”