Autism Spectrum Disorder is a neurodevelopmental disorder that is characterised by constant deficits in social interaction and communication, stereotyped behaviors, interests and cognitive delays. Scientists have known that one factor that contributes to autism is the abnormal brain growth but the relationship between the two or the genetic factors involved were never understood.
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have discovered the specific gene in which the mutation results in too much growth throughout the brain but somehow it only results in problems in social interactions, that’s what the mice models in the experiment have shown. Scientists found out that in terms of behavior, the mice were normal but there were consistent deficits in tests of social interaction and recognition, which is the major symptom of autism. This experiment concluded that most parts of brain adapt to this overgrowth which is why there is a minimal effect on behavior whereas the brain circuits involved in social behavior do not tolerate this overgrowth which is manifested as lack of social interaction.
The main focus of this study was the gene PTEN ( phosphatase and tensin homolog), the mutation in which was previously found to be associated with brain overgrowth and thus social deficits. Also another gene seems to be involved that regulates the levels of serotonin in brain. The study was first published on the journal Human Molecular Genetics.
After conducting the tests for autism related mood, anxiety, intellectual behaviors and circadian rhythm the researchers found the PTEN mutated mice showed altered social behavior. Some other changes were sex-specific in addition to social impairment, males showed abnormalities associated related to repetitive behavior, mood and anxiety, whereas females were more prone to changes in circadian activity and emotional learning.
Although this research confirmed the role of PTEN gene in developing autism and provided crucial information about genetic and development basis of this disorder, it also raised many questions like how exactly does this gene that normally influences growth can have relatively selective effects on behavior and social development.
One hypothesis proposed by the researchers is – maybe PTEN mutation desynchronize the normal pattern of growth in dopamine neurons that are relevant for social behavior. Whatever the reason, more research is needed to find out what steps are involved in the whole process that leads to autism.
- Source: TSRI