By King’s College London
The first ever genetic analysis of people with extremely high intelligence has revealed small but important genetic differences between some of the brightest people in the United States and the general population.
Published today in Molecular Psychiatry, the King’s College London study selected 1,400 high-intelligence individuals from the Duke University Talent Identification Program. Representing the top 0.03 per cent of the ‘intelligence distribution’, these individuals have an IQ of 170 or more – substantially higher than that of Nobel Prize winners, who have an average IQ of around 145.
Genetic research on intelligence consistently indicates that around half of the differences between people can be explained by genetic factors. This study’s unique design, which focused on the positive end of the intelligence distribution and compared genotyping data against more than 3,000 people from the general population, greatly enhanced the study’s power to detect genes responsible for the heritability of intelligence.
Researchers analysed single nucleotide polymorphisms (SNPs), which are DNA differences (polymorphisms) between individuals in the 3 billion nucleotide base pairs of DNA – steps in the spiral staircase of the double helix of DNA that make up the human genome. Each SNP represents a difference in a single nucleotide base pair, and these SNPs account for inherited differences between people, including intelligence. The study focused, for the first time, on rare, functional SNPs – rare because previous research had only considered common SNPs and functional because these are SNPs that are likely to cause differences in the creation of proteins.
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