ReviewAutism genetics

- Autism spectrum disorder has strong, complex and heterogeneous genetic underpinnings.
- The phenotypic expression of these genetic components is also highly variable.
- All autism genes are also involved in intellectual disability, and several in other disorders like schizophrenia.
- Autism genetics includes syndromic forms, CNVs or point mutations, mitochondrial forms and polygenic autisms.
- Genome-wide association studies and whole-exome sequencing have recently provided valuable contributions to the field.

Autism spectrum disorder (ASD) is a severe neuropsychiatric disease with strong genetic underpinnings. However, genetic contributions to autism are extremely heterogeneous, with many different loci underlying the disease to a different extent in different individuals. Moreover, the phenotypic expression (i.e., “penetrance”) of these genetic components is also highly variable, ranging from fully penetrant point mutations to polygenic forms with multiple gene-gene and gene-environment interactions. Furthermore, many genes involved in ASD are also involved in intellectual disability, further underscoring their lack of specificity in phenotypic expression. We shall hereby review current knowledge on the genetic basis of ASD, spanning genetic/genomic syndromes associated with autism, monogenic forms due to copy number variants (CNVs) or rare point mutations, mitochondrial forms, and polygenic autisms. Finally, the recent contributions of genome-wide association and whole exome sequencing studies will be highlighted.