Final answer:
Autism Spectrum Disorder (ASD) has both genetic and environmental etiological factors, and several hundred genes have been implicated in ASD. However, the causes of ASD are largely unknown, and more research is needed to determine definitive answers. Environmental exposures to various pollutants may function as triggers for the condition.
Step-by-step explanation:
Autism Spectrum Disorder (ASD) has both genetic and environmental etiological factors. Several hundred genes have been implicated in ASD, and expression in gene networks can depend on both genetic and environmental factors. However, the causes of ASD are largely unknown, except for some well-characterized genetic forms. Variants of several genes correlate with the presence of ASD, but many different mutations in different genes may be required for the disease to develop. Environmental exposures to various pollutants may function as triggers for the condition, but more research is needed to determine definitive answers.