Autism, or autism spectrum disorder (ASD), is a neurodevelopmental condition that typically includes abnormal social behavior with restricted and repetitive behaviors. ASD is often the result of a variety of factors, including genetic, environmental, and developmental.
Because autism is considered a “spectrum,” individuals can vary widely in their symptoms and severity. The range of symptoms, potential causes, and interventions can make it difficult to find the best approach for any one person. Many people with autism, or their caregivers, use genetic testing and counseling.
Types of genetic testing used in ASD
Experts use several types of genetic tests for individuals with autism.
Chromosomal Microarray (CMA) is usually the first-tier genetic test for ASD. CMA detects large, significant genetic changes, such as missing or extra chromosomes or chromosomal segments. Some of these variations are inherited from a parent, but others happen in the child’s own DNA. About 10 percent of individuals with ASD show a chromosomal disorder.
Whole Exome Sequencing (WES) tests for multiple genetic conditions at once. This test sequences all the exons, or protein-coding regions of the genome. WES can find smaller genetic changes that may be associated with ASD, and can help guide medical decisions and interventions.
Fragile X Testing specifically identifies fragile X syndrome, a common inherited cause of intellectual disability. This condition is caused by a mutation of the FMR1 gene that a child inherits from the mother. About 5 percent of individuals with autism have fragile X syndrome.
Whole genome sequencing (WGS) gathers comprehensive information on an individual’s entire genome, including both coding and non-coding regions. Although this method is complex and can identify many different genetic variations, it is also higher cost than other methods.
Healthcare providers or researchers may recommend targeted gene panels that look for specific genes already associated with autism and related disorders. This may be done after WGS or WES.
Are there limitations to genetic testing for autism?
Genetic testing has come a long way in the last two decades, but it is not a foolproof approach. Autism is a complex condition with numerous factors, genetic being only one of them. Even when a genetic component is identified, this does not apply to all individuals diagnosed with ASD.
Not every individual who carries a genetic variation associated with ASD actually has the condition, or to the same degree. In addition, other factors besides genetics can affect whether a person develops autism.
Genetic counseling should accompany any genetic testing for autism. This helps individuals, families, and caregivers understand the meanings of test results and the potential risks associated with the findings.
Genetic testing and counseling for autism may:
- Provide a better idea of what to expect as a child diagnosed with ASD grows
- Point to a strong genetic influence on a child’s autism
- Help families find the most effective interventions
- Identify other, potentially co-occurring conditions
- Allow a person with ASD to participate in specific research studies
- Guide family planning by evaluating the risk of autism with future pregnancies
Counselors can work with families to help them choose the best response to genetic testing results. Therapists and other health providers may collaborate with genetic counselors to ensure that an individual with autism receives the best type of therapy for their needs and capabilities.
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