Many genes have been implicated in autism; one of them is the CNTNAP2 gene. This gene (which is also implicated in specific language disorder) is most active during brain development in the frontal lobe. An imaging study involving 32 children, half of whom had autism, has revealed that regardless of their diagnosis, the children carrying the risk variant showed communication problems within and with the frontal lobe. The frontal lobe was over-connected to itself and poorly connected to the rest of the brain, particularly the back of the brain.
There were also differences in connectivity between the left and right sides of the brain — in those with the non-risk gene, communication pathways in the frontal lobe linked more strongly to the left side of the brain (which is more strongly involved in language), but in those with the risk variant, the communications pathways connected more broadly to both sides of the brain.
The findings could lead to earlier detection of autism, and new interventions to strengthen connections between the frontal lobe and left side of the brain. But it should be emphasized that the autistic spectrum disorders probably encompass a number of different genetic patterns associated with different variants of ASD.
It should also be emphasized that this gene variant, although it increases the risk of various neurodevelopmental disorders (such as specific language impairment, which has also been associated with this gene), is found among a third of the population. So the pattern of connectivity, although not ‘normal’ (i.e., the majority position), is not abnormal. It would be interesting to explore whether other, more subtle, cognitive differences correlate with this genetic difference.
Scott-Van Zeeland., A.A. et al. 2010. Altered Functional Connectivity in Frontal Lobe Circuits Is Associated with Variation in the Autism Risk Gene CNTNAP2. Science Translational Medicine, 2 (56), DOI: 10.1126/scitranslmed.3001344 http://stm.sciencemag.org/content/2/56/56ra80.abstract