Recommendations will have to be developed so clinicians have a guideline of who should be tested for genetic causes of autism. With the average test costing $2,000 to $5,000, insurers may question the validity of testing for a chromosomal anomaly that occurs in a mere 1% of autistic persons.
Looking Beyond Thimerosal
One of the most persistent theories about autism is that it is caused, at least in some cases, by exposure to thimerosal, which was used as a preservative in many vaccines until about 10 years ago, when manufacturers started removing it from their products. Numerous studies have failed to identify such a link, but many parents remain unconvinced.
A study by Schechter and Grether in the Archives of General Psychiatry is among the most recent to dispel the autism-thimerosal link. The researchers discovered that rates of autism continued to rise in California even after thimerosal had been removed from vaccines. “[T]ime trends are inconsistent with the hypothesis that thimerosal exposure is a primary cause of autism in California,” the authors write. However, “we support the continued quest for the timely discovery of modifiable risk factors for autism and related conditions.”
Eric Fombonne, MD, from the Department of Psychiatry at Montreal Children’s Hospital, expressed frustration in his accompanying editorial: “How many more negative study results are required for the belief to go away, and how much more spending of public funds on this issue could even be justified?”
While remaining neutral about thimerosal, Wolpert acknowledges the “need [for] more research funding—for all aspects, not just genetics.”
Since pharmacologic therapy for autism, let alone a cure, is little more than a dream at this stage, it might be beneficial to explore ways to address the issues experienced by patients and parents living with autism. “How are we going to help the parents and patients who already have this [diagnosis]?” Wolpert asks. “What factors in a family or educational system help a child to achieve his or her highest level of ability?”
Identification of additional genetic factors will also open the doorway to exploring the role of environmental factors in autism. “If you can control for one variable in a study, then you can examine the others,” Wolpert points out.
Progress may be slow, but clinicians, parents, and patients have reason to hope. “The bad news is 85% to 90% of autism is still unexplained,” Wolpert says. “Then again, what great progress! Ten years ago, we knew autism had a genetic basis, but that’s all we knew. Now, we have causative genes and genes that increase risk. We’re making headway.”