A study to be published later this month in the journal Molecular Autism confirms previous research that people with Asperger Syndrome (AS) are more likely to carry specific variations in a particular gene. More strikingly, the study supports existing findings that the same gene is also linked to how much empathy typically shown by individuals in the general population. The research was carried out by a team of researchers led by Professor Baron-Cohen at the Autism Research Centre at Cambridge University. Asperger Syndrome is an autism spectrum condition. The researchers looked for sequence variations (called single nucleotide polymorphisms or SNPs) in the gene known as GABRB3 in a total of 530 adults – 118 people diagnosed with AS and 412 people without a diagnosis.
Rather than studying people on the autistic condition spectrum, this new study looked only at people with AS, as a well-defined subgroup of individuals within this range. The researchers examined the gene GABRB3 which regulates the functioning of a neurotransmitter called gamma-aminobutyric acid (GABA) and which contains a number of SNPs that vary across the population. The volunteers were tested for 45 SNPs within this key gene. The team had previously found that SNPs in this gene were more common in adults with AS and also showed a relationship with empathy levels and tactile sensitivity (how sensitive people are to being touched) in the general population. Testing a new sample of volunteers who had not taken part in previous studies, the researchers found that three of the SNPs were again more common in adults with AS, and two different SNPs in the same gene were again related to empathy levels in the general population, confirming that the gene is involved in autism spectrum conditions.
Professor Baron-Cohen said: “We are excited that this study confirms that variation in GABRB3 is linked not just to AS but to individual differences in empathy in the population. Many candidate genes do not replicate across studies and across different samples, but this genetic finding seems to be a solid result. Research now needs to focus on where this gene is expressed in the brain in autism, and how it interacts with other genetic and non-genetic factors that cause AS.”