Autism spectrum disorders are characterized by impaired communication, impaired social relationships, and repetitive behaviors or narrow interests. Current estimates indicate that between 1 in 90 and 1 in 110 children in the United States are diagnosed with an autism spectrum disorder (ASD). A genetic component to autism has long been recognized, as the parents of a child with autism are much more likely to have another child with autism (5-10% chance) than parents who do not already have a child with autism (~1% chance). However, identifying specific genetic causes has been difficult, and known genetic causes are only discovered in a small percentage of cases.
Identifying the cause for a child’s autism is typically a long process, involving many tests and evaluations, and frequently yields no definitive answers. In only approximately 10-20% of cases can a specific genetic etiology be determined for an individual’s autism. The major genetic causes of autism include cytogenetic abnormalities (large missing or rearranged pieces of an individual’s chromosomes which can be viewed under a microscope), copy number variants (smaller deletions and duplications of genetic material), and changes in single genes. Identifying a specific genetic cause for an individual’s autism allows parents and other family members to better understand their risks to have another child with the same condition. Additionally, if a specific cause is identified, it can provide guidance for parents and doctors about what other medical problems may arise for a child, and potentially what treatment options might be most effective.
A paper in the July issue of Cell reports on a new genetic cause of autism, mutations in the CHD8 gene. Mutations in this gene were present in approximately .5% of the thousands of individuals with an autism spectrum disorder that were studied. Individuals with these mutations shared many common defining features, delineating, perhaps, a distinct subtype of autism. Researchers hope to use information like this to learn more about how changes in these specific genes lead to autism, with the goal of potentially developing medications and more effective treatments. To learn more about the genetics of autism spectrum disorders, visit ncbi.nlm.nih.gov . For other autism resources, visit AutismSpeaks.org.