4000 genetic variants linked to brain structure

A study assessing over 36,000 brains has uncovered more than 4000 genes linked to brain structure and development.

Led by researchers at the University of Cambridge, UK, the team used MRI scans and genetic data to assess 13 different brain traits including the area and thickness of the outer layer of the brain known as the cortex, and how the cortex is folded. The work, published in Nature Genetics, helps to unveil how our genes contribute to brain development and may aid in the advancement of therapies for neurological and psychiatric conditions.

First author Dr Varun Warrier from the University of Cambridge said: 'One question that has interested us for a while is if the same genes that are linked to how big the cortex is – measured as both volume and area – are also linked to how the cortex is folded. By measuring these different properties of the brain and linking them to genetics, we found that different sets of genes contribute to folding and size of the cortex.'

The brain is a complex organ with large variations between individuals. Due to practical challenges studying it during development, little is known about how it develops and how our genes are involved. In this study, different structural features of the brain were measured using MRI scans from 36,663 adults and children from the UK and US. Data was taken from two cohorts, the UK Biobank and the Adolescent Brain Cognitive Development Study. The team then used a statistical technique called a meta-analysis to look for associations between the brain measurements and variations in genes from whole-genome data.

They were able to identify 4349 individual genes that were associated with variations in the measurements which included the area, volume, and thickness of the cortex, cortical folding, and neuron density. They also found that these genes overlapped with genes associated with cephalic conditions in which head sizes are much smaller or bigger than the general population.

While this is the largest study of the genetics of the brain and has contributed to our understanding of brain development, a lot remains unknown about exactly how our genes influence the structure and function of the brain.

Dr Richard Bethlehem, University of Cambridge, 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.'