Current knowledge on the genetics of autism and propositions for future research

Autism spectrum disorders (ASD) are a heterogeneous group of neuropsychiatric disorders characterized by problems in social communication, as well as by the presence of restricted interests, stereotyped and repetitive behaviours. In the last 40years, genetic studies have provided crucial information on the causes of ASD and its diversity. In this article, I will first review the current knowledge on the genetics of ASD and then suggest three propositions to foster research in this field. Twin and familial studies estimated the heritability of ASD to be 50%. While most of the inherited part of ASD is captured by common variants, our current knowledge on the genetics of ASD comes almost exclusively from the identification of highly penetrant de novo mutations through candidate gene or whole exome/genome sequencing studies. Approximately 10% of patients with ASD, especially those with intellectual disability, are carriers of de novo copy-number (CNV) or single nucleotide variants (SNV) affecting clinically relevant genes for ASD. Given the function of these genes, it was hypothesized that abnormal synaptic plasticity and failure of neuronal/synaptic homeostasis could increase the risk of ASD. In addition to these discoveries, three propositions coming from institutions, researchers and/or communities of patients and families can be made to foster research on ASD: (i) to use more dimensional and quantitative data than diagnostic categories; (ii) to increase data sharing and research on genetic and brain diversity in human populations; (iii) to involve patients and relatives as participants for research. Hopefully, this knowledge will lead to a better diagnosis, care and integration of individuals with ASD.