Having completed the clinical validation of its ATScan test for autism spectrum disorder, CombiMatrix last month announced that it would make the technology available through its CLIA labs.
CombiMatrix said that the launch of the microarray-based test is timely since it follows the American Academy of Pediatrics’ recently updated guidelines recommending all children be screened at least twice for autism before the age of two.
CombiMatrix CEO Amit Kumar told Pharmacogenomics Reporter last month that the company is currently evaluating whether to submit the test to the US Food and Drug Administration for approval.
“It’s well known that if you start treatment, counseling, education, social interaction types of things, with autistic children early then you lessen their symptoms,” he said. “So if you know that a child of one or two years old has a high probability of becoming autistic, then that child can be monitored very quickly and closely, and a number of programs can be begun with that child so that the symptoms can be lessened throughout his or her life.
Current screening methods to diagnose autism involve a number of cognitive tests that physicians administer after a child begins to demonstrate symptoms of the condition. However, most of these cognitive tests are subjective, according to Kumar.
“Physicians who deal with these things are very aware that early intervention is important,” Kumar continued. “What they don’t have are good objective tests, like [the one CombiMatrix has launched], to determine predisposition.”
CombiMatrix’s ATScan, based on bacterial artificial chromosome array, comparative genomic hybridization technology, detects known genomic copy-number variations associated with ASD. The company launched the test in partnership with Steve Scherer, director of the Centre for Applied Genomics at the Hospital for Sick Children in Toronto, who recently correlated the SHANK3 gene on chromosome 22q to autism susceptibility. The results of Scherer’s study were published in the The American Journal of Human Genetics last month.
Timely or Too Soon?
According to CombiMatrix, although researchers continue to debate the causes of autism, the test is in line with current American Academy of Pediatrics treatment guidelines recommending screening kids before the age of two.
Additionally, ASD is one of the most common pediatric developmental disorders. According to the Centers for Disease Control, approximately one in 150 children born in the US are diagnosed with the disorder.
Kumar noted that although the company is considering submitting the test for FDA clearance, launching it through its CLIA laboratory allows the company to easily update the test as more genetic correlations become known. In the next 18 months, Kumar expects researchers to publish data from new studies linking autism to genetics.
Kumar said the test is “not absolutely comprehensive,” noting that it does not capture all of the genetic factors contributing to ASD.
“Our test is designed to look at some specific genetic markers that predispose children to autism,” he said. “If a child has those markers then there is a high likelihood that the child will be diagnosed with autism some time in the future. If the child does not have those markers, then it does not necessarily mean that the child will not get autism. It just means that the child will not be autistic due to those genetic factors that we looked at.”
“At this time, unless they are known to be at risk due to a sibling or a parent having a known genetic abnormality, children should have genetic screening when impairments are clear and a diagnosis is made, not as part of universal screening.”
The ATScan is also being used to determine childhood predisposition to several other childhood disorders, such as Down and Angelman syndromes. The test costs $1,600 and is reimbursed by Medicare. Based on the cost of the test and more than 4 million births registered by the US Census in 2005, CombiMatrix’s test is entering into a market potentially valued at $44 million.
However, according to one prominent neurodevelopmental pediatrician, it may be too soon to promote universal genetic screening for autism.
“There is not enough evidence to support this type of genetic screening for all children to establish their risk of ASD,” Scott Myers, a neurodevelopmental pediatrician at Geisinger Medical Center, and an assistant professor of pediatrics at Jefferson Medical College, told Pharmacogenomics Reporter in an e-mail.
Myers, who helped write two clinical reports to help pediatricians identify and manage autism early, noted that while microarray-based tests for the disorder are “getting better all the time,” the specificity and sensitivity of these tests need to be further validated. In addition, researchers must determine whether screening improves outcomes.
Myers further noted that while the technology does not support a recommendation for universal genetic screening for pediatric autism, children who have a known familial genetic predisposition to the disorder should be tested.
“To be accepted as a screening test, the array would have to be studied prospectively in a large population to determine sensitivity, specificity, positive predictive value, and negative predictive value (which are likely to be low),” Myers said. “It would be important to determine whether the positive results have an impact on outcomes … [and] a cost-benefit analysis would then be warranted.”
Myers also said that while genetically screening children for predisposition mutations might allow doctors to intervene earlier, “it is not clear what that intervention would be.”
“We can only intervene with specific impairments at this time, and if those impairments aren’t present yet, the role for earlier ‘intervention’ is only theoretical,” he wrote. Even after knowing that a child might be genetically predisposed to autism, at this point, doctors can only recommend standard interventions like providing a stimulating environment or watching the child carefully for impairments.
Given the current state of the technology, universal genetic screening of children may not be appropriate, Myers maintained. “At this time unless they are known to be at risk due to a sibling or a parent having a known genetic abnormality, children should have genetic screening when impairments are clear and a diagnosis is made, not as part of universal screening,” he said. “This may change in the future.”