ABSTRACT
Understanding the causes of autism spectrum disorders (ASD) is complex. The heterogeneity of both presentation and etiology of ASD is increasingly recognized. Both genetic and environment factors are associated with increased risk of ASD. Genetic differences can be hereditary or de novo. This chapter outlines syndromes and dysmorphic features that can be present in children with ASD. After children are identified as having an ASD, genetic microarrays or exome sequencing tests may be ordered. In addition to genetic risk factors, environmental factors are associated with the risk of ASD. The author outlines current research on environmental factors such as parental age, birth history, environmental exposures, maternal substance use, and maternal antidepressant use. The chapter provides tips for talking with families about genetics and concerns about vaccinations.
