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What causes ? Every answer seems to unlock more questions, but scientists are making progress. In a recent JAMA review, researchers laid out known genetic risk factors associated with the disorder, how they might be used to develop future treatments, and what recent findings mean for parents of children with the condition.

Revealing Origins

Researchers have identified dozens of tied to autism, but they estimate that there are hundreds. In genetic analyses of patients with autism, the likelihood that a relevant gene is identified is still less than 50 percent, says Rebecca Muhle, a child and adolescent psychiatrist at the Yale School of Medicine. "It doesn't mean there isn't something there, just that we can't detect it yet." Research on how autism plays out in the brain is also advancing. Studies suggest autism-related differences in brain development exist within the first year of life—underscoring the usefulness of early diagnosis and behavioral interventions.

The Case For Testing

Despite the inconclusiveness of genetic testing, the researchers recommend it for all individuals who have already been diagnosed with autism. Identification of any known autism-related mutation can be a source of comfort, according to Muhle: Many of the parents she sees are convinced their actions contributed to their child's condition, and detecting known genetic risk factors can help stem undue . Genetic information can also improve a clinician's understanding of a patient's overall prognosis, including co-occurring conditions that might otherwise go unmonitored.

Future Treatments

Genetic test results could eventually lead to treatments based on neurobiology. If researchers can determine the effect of genetic variants on particular cell types in the brain, "we can better focus on those types of cells and try to figure out how to improve their function, repair them, or even prevent them from getting damaged," Muhle says. Such treatments are years, perhaps even decades, away. Autism is not a single disorder but rather a set of overlapping symptoms. The pathway to targeted treatments, Muhle says, starts with building a more robust genetic database.