Autism Spectrum Disorders (ASDs) are characterized by impairments in social interaction and communication, as well as restrictive behaviours and interests. These life-long disabilities affect more than 1 in 250 individuals. It has been shown that early diagnosis is essential for children with ASD: the earlier intervention is initiated, the better the outcome. However, affected children are commonly not definitively diagnosed until they are three years of age or older. Sibling, twin and family studies have shown that ASDs are largely genetic in origin and certain chromosomal regions harbouring possible ASD susceptibility genes have been identified. Recent studies suggest that between 5 and 48% of individuals with autism exhibit chromosomal anomalies. This suggests that small chromosomal anomalies, such as microdeletions and microduplications, may be relatively common and clinically important markers for identifying underlying causes of, and susceptible gene regions for, ASDs. Dr. Suzanne Lewis is researching the genetic susceptibilities of ASD, using a novel method for the analysis of regional changes in DNA called microarray-based comparative genomic hybridization (array-CGH). Using this method she is identifying and characterizing chromosomal abnormalities in 100 subjects with ASD. In parallel, Dr. Lewis is also researching ASD phenotypes – genetic influences in combination with respective behavioural, physical, medical, environmental and family findings. Dr. Lewis aims to build a research pathway that identifies genetically distinct subgroups of ASD that also share unique clinical phenotypes. Through researching this genotype/phenotype correlation Dr. Lewis ultimately hopes her research will contribute to a better understanding of the genetic causes and consequences of autism and help in developing methods for the very early identification of infants and families at risk for autism.