Genetic variants lend insight into behavioural traits

THREE genetic variants have been found to be significantly associated with educational attainment in certain individuals, according to a recent study involving Sir Charles Gairdner Hospital.


The results showed three SNPs significantly associated with educational attainment, one associated with years of education, and two with college completion.

The discovery of genetic variants (ways in which people’s genomes differ) associated with behavioural traits, gives insight into the biological pathways of human behaviour.

However, most existing studies have methodological limitations; meaning a small sample size and a lack of replication.

An international collaboration of 130 institutions conducted the first genome-wide association study (GWAS) of educational attainment in a sufficiently large sample size.

Cornell University expert Dr Daniel Benjamin says, “virtually all existing studies use sample sizes in the range of 100-2,000”.

“The tiny effects for genetic variants suggest that identifying genetic influences on challenging behavioural traits should include at least tens of thousands of participants,” he says.

The research studied approximately two million genetic variants called single nucleotide polymorphisms (SNPs).

SNPs are the smallest and most common type of genetic variants.

Using combined data from 54 cohorts with 126,559 individuals, they achieved a sample size about 10 times larger than the largest previous study.

They used two different variables to measure educational attainment including a quantitative variable defined as an individual’s years of schooling, and a binary variable for whether or not an individual had completed college.

The results showed three SNPs significantly associated with educational attainment, one associated with years of education, and two with college completion.

All three SNPs were also found in the replicates.

“This is important, it represents a separate test. If the variants were not associated with education, it’s unlikely all three would replicate in an independent sample,” Dr Benjamin says.

The observed effect sizes of these SNPs however are small, explaining only about 0.02 per cent of the variation in years of education.

However, combining all the genetic data, (significant and non-significant SNPs) to predict educational attainment and PBS based on SNPs, could explain just over two per cent of the variation in how many years of education they attained.

“Educational attainment, like all complex behaviour is influenced by large numbers of genetic and environmental factors. This study focuses on just a tiny piece of the puzzle,” Dr Benjamin says.

The researchers stress that they have not found the gene for educational attainment or cognitive function.

Nor does it show that an individual’s level of educational attainment is predetermined.

“Identifying genetic variants that contribute to differences in educational attainment leads to insights regarding the biological pathways underlying the outcome,” he says.