Around 1% of the global population has intellectual disability (ID, also known as learning disability), meaning lifelong difficulties with cognitive function.  Until recently, the cause of each person’s ID was usually unknown.  With recent advances in genomic technologies, it is now possible to find a specific cause (genetic diagnosis) for the majority of people with severe ID.  This opens up new opportunities to understand how each rare genetic diagnosis affects brain development, cognition and valuable outcomes such as mental health and social inclusion. 

A current area of debate is whether genetic diagnosis can predict which young people with ID will develop features of autism. This is a difficult problem to address because of the complex and variable aspects of autism spectrum disorder, and the very large number of rare genetic diagnoses to investigate. 

In this new publication, scientists at the MRC CBU, broke down this problem in a number of steps.  First, we worked out which autism-related characteristics tend to occur together within young people with ID (defining autism “dimensions”, rather than a single disorder).  We found three dimensions – flexibility, social understanding and social motivation.  Then we grouped young people with ID according to the biological functions of their genetic diagnoses (functional networks).  This allowed us to observe a link between regulation of gene expression (chromatinopathies) and one autism dimension – inflexibility.  Finally, we explored the predictors of autism dimensions within each functional network group.  We found that two out of three autism dimensions are closely tied to ADHD characteristics within the chromatinopathy group.  In contrast, anxiety seems to be a stronger predictor of autism dimensions (in particular social motivation) within the synaptopathy group.

In summary, our results show that there ARE links between genetic diagnoses and autism, but these links are not straightforward – predicting each individual’s likelihood of autism needs to take into account many other factors in addition to their genetic diagnosis.  We are hopeful that, with further research, genetic diagnosis will give us insights into the reasons why each person may be more or less likely to develop autism characteristics.  The links between a genetic diagnosis and autism are not likely to be fixed from the outset.  Rather, our current view is that genetic diagnosis can influence dynamic aspects of brain development which shape (and are shaped by) interactions between a child and their environment during their early years.

The full paper can be read here: https://rdcu.be/cb4NX