Scientists from Imperial College London have identified two gene networks that are linked to human intelligence.
The research, published in Nature Neuroscience, is the first to identify specific genes associated with intelligence.
'We know that genetics plays a role in intelligence but until now haven't known which genes are relevant. This research highlights some of genes involved in human intelligence, and how they interact with each other,' said lead author of the study, Dr Michael Johnson.
The researchers first looked at gene expression in mouse and human brain samples to identify genes associated with cognitive ability. This detected two gene network clusters, known as M1 and M3, the first containing over 1000 different genes and the second 150.
Then genetic analysis was undertaken on about 6700 individuals with neurodevelopmental disease, intellectual disability and epileptic encephalopathy who had taken IQ tests to assess cognitive abilities, memory, attention and reasoning as part of a family health study. These participants were compared with approximately 1000 healthy control participants.
This showed that genes influencing intelligence and ability of healthy people are the same genes that impaired cognitive ability and caused neurodisability, such as epilepsy, when mutated.
In particular, exome sequencing found that mutations in genes in the M3 network were over-represented in the cohort with neurodevelopmental disease in comparison to the control population.
Dr Johnson said that, although each network contains hundreds of genes, it is likely that they have a 'master switch'. 'What’s exciting about this is that the genes we have found are likely to share a common regulation, which means that potentially we can manipulate a whole set of genes whose activity is linked to human intelligence.
'Our research suggests that it might be possible to work with these genes to modify intelligence, but that is only a theoretical possibility at the moment – we have just taken a first step along that road.'
Genetics is thought to contribute to up to 75 percent of human intelligence, but no genes or gene networks had previously been identified as being involved. While modification of intelligence may be theoretically possible, other experts have warned that genetics is not the only determinant at play.
Darren Griffin, Professor of Genetics at the University of Kent, who was not involved in the study, told the Telegraph: 'Genetics is the science of inheritance, not pre-determinism, and there is no substitute for hard work and application.'
However, the authors say that identification of gene clusters associated with cognitive ability could help us understand how genetic risk variants for neurodevelopmental disease and related cognitive phenotypes exert their effects in the developed human brain.
'Eventually we hope that this sort of analysis will provide new insights into better treatments for neurodevelopmental disease, such as epilepsy, and ameliorate or treat the cognitive impairments associated with these devastating diseases,' said Dr Johnson.