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Schizophrenia or bipolar disorder in parents or siblings may be associated with increased risk of autism spectrum disorder, suggested a study in Archives of General Psychiatry.
Dr Paul Tiffin, Clinical Senior Lecturer at Durham University, said:
“The publication of this study is to be welcomed as it provides the first robust and consistent evidence of a general genetic link between autism spectrum disorders and the psychoses. The methodology was robust and the researchers used data drawn from well assembled case registers. However, it will still remain challenging to identify the actual genes involved in pre-disposing to both types of disorder.”
Dorothy Bishop, Professor of Developmental Neuropsychology, Dept of Experimental Psychology, University of Oxford, said:
“The association between schizophrenia in parents and autism in children is important in suggesting that genetic variants may confer a rather general risk for a range of disorders, rather than having highly specific effects. But this paper omits some key information that is important for assessing its clinical significance, namely how many children of those with and without schizophrenia developed autism. From other data we can estimate around 1 per 500 children in Sweden developed autism in the period of this study; this paper suggests that the rate is increased to around 1 per 170 for parents with schizophrenia. Statistically, this is a significant association, but the risk of a child with autism in absolute terms remains low for both kinds of parents.”
Dr Diana Prata, NIHR Post-Doctoral Fellow, Institute of Psychiatry, King’s College London, said:
“Interestingly, the prevalence of schizophrenia in parents of ASD patients is higher than that of ASD itself. This indicates a large overlap of genetic factors increasing risk for these disorders and probably their strong interaction with environmental (and epigenetic) factors. Most importantly, this study robustly shows that having a parent or sibling with ASD confers a 3-fold increase in risk of developing this type of disorder, which makes these the risk factors with the largest impact found so far. However, how this may improve prevention or clinical guidelines is not clear.”
Margaret Esiri, Professor of Neuropathy, University of Oxford, said:
“As the introduction to this paper makes clear, there are already pointers to an overlap between genetic risk factors for schizophrenia and autism so this paper’s findings are not entirely unexpected. They add to the evidence for such an overlap. Since many of the genes that have been implicated in risk for both schizophrenia and autism involve proteins that are thought to have important roles in the development of synapses – the points of close apposition between one nerve cell and another – the fact that an overlap in risk between the two conditions is gaining credence is also not unexpected.”
Professor Nick Craddock, Director of the National Centre for Mental Health, Cardiff University, said:
“This important population study fits with recent molecular findings in showing a biological relationship between these disorders. Better understanding of the underlying brain biology will give psychiatry better tools for diagnosis and management of these disabling conditions and improve the lives of millions of people around the world.”
‘Family History of Schizophrenia and Bipolar Disorder as Risk Factors for Autism’ by Sullivan, P. et al. , published in Archives of General Psychiatry on Monday 2nd July.