The Genetics of Autism

Autism spectrum conditions (henceforth ‘autism’) refer to a group of neurodevelopmental conditions involving difficulties in social interaction and communication and unusually repetitive and restricted behaviours and interest. Twin and family studies have established a significant heritability for autism. Autism is polygenic with variations across the allele frequency spectrum contributing to risk. Early linkage and candidate gene association studies were statistically underpowered to identify significant loci. Current genome-wide association studies have identified significant positive genetic correlation between autism and various measures of cognition. The use of genetic microarrays and next-generation DNA sequencing has identified tens of genes and copy number variants associated with autism. In addition, RNA microarray and sequencing studies of postmortem brain samples have identified transcriptionally altered genes and pathways in autism. Multiple lines of evidence converge on altered glial, synaptic and chromatin pathways as contributing to autism risk.