Genetic test for Autism and
Gene Research Bring New Hope
Autism is on the rise. The number of people diagnosed with autism has increased significantly in recent years, prompting more research to better understand the condition, provide genetic testing and seek more targeted and personalized treatments. A new study on gene mutation may give more impetus to these efforts.
Autism is a developmental disorder that presents a great number of challenges with social skills, communication and behavior. Initial symptoms usually appear in the first two years of life, but the condition can be diagnosed at any age. It is estimated that 1 in 59 children are affected by the disorder today, numbers that have been steadily climbing each year. One reason for this increase is that autism has grown to include many conditions that were not previously classified as autism. There are now more than 500 different mutations associated with the disorder, making diagnosis more and more difficult. Genetic test for autism is a way to identify these mutations.
Genetic test for autism
Autism refers to a broad range of conditions that are primarily genetic. According to Suma Shankar, a medical geneticist at the University of California, Davis, up to 60% of autism cases may be attributed to underlying genetic causes. For this reason, genetic testing to identify the mutations associated to certain autistic conditions can provide valuable information for families and researchers. While genetic tests cannot diagnose autism, they can offer new insight on treatments and prevention and help researchers classify mutations associated to the disorder.
Information provided by genetic tests can help establish the potential risks or benefits involved in various treatments for specific autism patients, identify underlying medical risks and alert families to other health problems that may be linked to a mutation, such as heart defects or immune system disorders, which may require a different course of treatment. Tests may also help clinicians provide more targeted behavioral therapies that could lead to the development of new drugs in the future for underlying neurochemical abnormalities.
Another advantage to genetic testing is that it provides a way for scientist to uncover the full list of mutations related to autism. John Constantino, for example, and his team of researchers at the autism clinic at Washington University in St. Louis, Missouri offer exome sequencing to anyone who visits the clinic. Through these tests, Constantino’s team has identified genetic variants that predispose autistic people to subtypes of epilepsy that can be treated with specific drugs. They have also been able to match patients with the same mutation and alter treatments based on examining their case reports. Access to more data also means researchers can put together databases that clinicians can use to look up different mutations. Currently ClinVar and ClinGen are two databases funded by the National Institutes of Health that list genes and specific variants found in individuals with known conditions. With more research and testing, the information in these databases will become increasingly more valuable to developing potential therapies.
Making genetic testing more accessible
Despite the advantages the information retrieved from genetic tests give us, many families never have the chance to offer their child genetic testing. Firstly, many people do not even know the tests are available. Clinicians who treat autistic children rarely receive training about the benefits of the tests and simply do not order them. Secondly, the tests are extremely expensive and insurance companies are reluctant to reimburse for them because there is no proof that the results of the tests can change autism care. This may change in the future as researchers are making great efforts to put together a list of genes that have strong clinical ties to autism. “There are no clear criteria for assigning a gene to an autism list, [and] most of the companies do not provide a rationale for inclusion,” says co-lead researcher Ny Hoang, a genetic counselor at the Hospital for Sick Children in Toronto, Canada. The group’s goal is to make the list and a set of guidelines publicly available and to update both regularly.
Finally, not everyone agrees that genetic testing is worth the cost. Jennifer Singh, a sociologist at Georgia Tech and author of the book Multiple Autisms: Spectrums of Advocacy and Genomic Science, says, “I don’t know that the knowledge gained from just having a gene that’s linked to autism is that beneficial. It gives some information, but to what degree does that change treatment or prognosis? At the end of the day you have to address the issues that are at hand, whatever they might be.” Singh thinks it would be more beneficial to spend the extra money on resources and behavioral therapies that can help the child improve his or her future.
The fact is, the genetics of autism are quite complex and only further research can offer more answers. A recent study provides a new link between gene mutations and autism that may give new meaning to genetic test for autism and provide new opportunities for novel treatments in the future.
Study on a gene mutation
Diverse studies have found an association between the gene SCN2A and severe forms of autism. While other gene mutations linked to autism are thought to alter the brain before birth, this new gene mutation seems to occur close to the onset of symptoms. The SCN2A gene is known to impede communication between brain cells.
In a recent study, published June 20, 2019 in the journal Neuron, researchers from UC San Francisco deleted one copy of the SCN2A gene in mice, resulting in a weak connection between neurons and hampering communication channels. “Combined with our earlier research that first laid out how autism-associated mutations in SCN2A alter sodium channel function, we now have a good idea of the cell type, brain region, and the change in functions that result in autism when SCN2A is affected”, said Kevin Bender, PhD, an assistant professor of neurology at UCSF and senior author on the paper.
This study offers hope for a potential therapy for autism. If brain changes occur before the first year of life, it will be difficult to intervene. If, however, brain changes occur in later phases of brain development, intervention may be possible. Scientists are currently seeking ways to correct the SCN2A mutation in mice, which could eventually lead to gene therapy treatments in humans. “This finding gives us hope, because even in kids who are diagnosed relatively late, there’s still the potential for a therapeutic”, says Stephan Sanders, BMBS, PhD, an assistant professor of psychiatry at UCSF, who was a member of the Yale team that first identified the SCN2A gene as a gene implicated in autism in 2012.
Gene discovery, research on gene mutation and genetic testing can all be linked to a more promising future for autism patients and their families. While the fundamental genetic architecture of autism is still unknown, dramatic progress is being made in several areas of research, which has heightened interest in supporting research efforts. It is hoped that these efforts may eventually lead to improved diagnosis, treatment, and prognosis of autism.
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