Genetic Tests for Autism
Updated on June 4th, 2019
Autism is a spectrum disorder. This means that there are a wide range of lifelong symptoms that vary in severity and in form.
In general Autism Spectrum Disorder (ASD), as it is officially known, is characterized by impaired social and communication interactions. Autistic individuals will also engage in repetitive patterns of behavior, activities or interests.
According to the Center for Disease Control, about 1 in every 59 children in the United States have been diagnosed with autism by age 8 with parents typically noticing some form of developmental impairment by a child’s first birthday. Boys are also four times more likely than girls to be diagnosed with autism.
Is autism genetic?
Genetics are closely linked to autism, but the medical community is still attempting to determine exactly what the genetic and non-genetic factors are that contribute to autism.
It’s estimated that about 15% of children with autism have been identified as having a genetic disorder, such as Fragile X syndrome, tuberous sclerosis, Down syndrome, or other chromosomal abnormalities, copy number variants, and single gene mutations.
As genetic testing becomes more advanced, researchers expect that the percentage of people with a genetic cause related to autism will increase. Autism can also be caused by other non-genetic factors, such as such as exposure to a maternal immune response in the womb or complications during birth.
It should be noted that among the genetic causes of autism, Fragile X Syndrome (FXS) is the most common known inherited single-gene disorder, and accounts for an estimated 1% to 6 % of all autism cases.
FXS is a genetic condition that causes intellectual disability, behavioral and learning challenges, and various physical characteristics. No one person will have all the outward manifestation of FXS, but they will be characterized by one or more of the following:
- Behavioral characteristics include ADD, ADHD, social anxiety, hand-biting and/or flapping, poor eye contact, sensory disorders, increased risk for aggression, and autism and autistic-like behaviors.
- Intellectual disabilities include a range from moderate learning disabilities to more severe intellectual disabilities.
- Physical features may include large ears, long face, soft skin, and large testicles (called “macroorchidism”) in post-pubertal males.
- Connective tissue problems may include ear infections, flat feet, high arched palate, double-jointed fingers, and hyper-flexible joints.
- Disposition: They are very social and friendly, have excellent imitation skills, have a strong visual memory/long term memory, like to help others, are nice, thoughtful people and have a wonderful sense of humor.
Fragile X syndrome is a gene mutation caused by the expansion or lengthening of the FMR1 gene on the X chromosome. When the gene lengthens, it switches off production of a protein that is involved in brain development and other functions.
The FMR1 DNA Test (sometimes called the Fragile X DNA Test) detects more than 99% of people with FXS or premutation carriers.
Having a genetic diagnosis of autism in addition to an ASD diagnosis can help families in several ways. Most notably, it can alert them to other potential conditions, including FXS.
Because of the link between autism and FXS, it is often recommended that children diagnosed with autism get a genetic evaluation for FXS as well.
Autism has a strong genetic basis, although the genetics of autism is complex and it isn’t clear whether autism is explained more by multigene interactions or by rare mutations with major effects.
Overall, genetic analysis of autism has been inconclusive. For each autistic individual, mutations in more than one gene may be implicated. Mutations in different sets of genes may be involved in different autistic individuals.
Can autism be diagnosed through genetic testing?
To say that Autism Spectrum Disorder can be diagnosed through genetic testing is a bit misleading. However, genetic testing does play a role when it comes to the potential presence of autism.
Autism is a childhood-onset condition that is characterized by observable differences in social interaction, communication and development. The diagnosis of autism is typically made by psychologists, developmental pediatricians, psychiatrists, and neurologists.
To diagnose autism, information from parents and teachers must be gathered relating to a child’s milestones, skills, and behavior. Standardized tests are also employed to evaluate language, learning, and social interaction.
This means autism is a behaviorally defined condition that can’t be diagnosed through a genetic test. It also can’t be diagnosed through and MRI, EEG or other non-behavior methods.
Autism can only be diagnosed based on the presence or the absence of behavioral or developmental features.
For the record, the standard reference used to diagnose mental and behavioral conditions—including autism—is the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).
Genetic testing can help identify the underlying causes of autism, but it isn’t accurate to say that genetic testing can prove or disprove the presence of autism in a child.
Studies suggest that some people have a genetic predisposition to autism. Research is attempting to determine the specific genetic factors associated with the development of autism.
In families with one child with ASD, the risk of having a second child with the disorder also increases. Many of the genes found to be associated with autism are involved in the function of the chemical connections between brain neurons.
Autism risk also increases in children born to older parents. Scientists aren’t quite sure why, but they are exploring the link between genetics and autism as it relates to the parents ages. It is one of several environmental factors that are being looked at and how they influence ASD risk.
The importance of identifying genetic disorders
All diseases have a genetic component, but there is still a lot to be learned about the extent and detail that genes play in diseases.
Understanding the genetics and the genetic disorders that can take place behind diseases is critical to developing early diagnostic testing, new treatments and possible interventions to either help or minimize the impacts of a disease or the depth of its severity.
Identifying genetic disorders and their causes helps to determine if a mutation was inherited or if it was developed due to external environmental causes such as viruses or toxins.
There are several types of genetic tests that can be performed as a way to identify genetic disorders:
Prenatal diagnostic testing can be used to detect changes in a fetus’s genes or chromosomes and is performed when couples have an increased risk of having a baby with a genetic disorder. A tissue sample is taken through amniocentesis or chorionic villus sampling.
Newborn screening provides early detection of certain diseases that can help intervene to prevent the onset of symptoms or to minimize the severity of the disease.
Carrier testing helps prospective parents learn if they have recessive alleles for genetic diseases such as sickle cell anemia, cystic fibrosis and other related conditions. This type of testing is generally carried out for people who have a family history of a genetic disorder or in certain ethnic groups that have been identified as having a greater propensity for a genetic condition.
If both parents are tested, the test can provide information about a couple’s risk of having a child with a genetic condition.
Predictive genetic testing identifies individuals at risk of getting a disease before the onset of symptoms. These tests can be particularly useful if an individual has a family history of a specific disease (such as cancer) and an intervention is available to prevent the onset of disease or minimize disease severity.
Why genetic tests matter for autistic people
When a person is diagnosed with a genetic cause for ASD that has been confirmed through behavioral testing, it can provide important information regarding the prognosis, treatment and family implications.
It’s important to note that a positive genetic test result alone cannot predict whether a child’s symptoms meet criteria for ASD or any other behavioral disorder. Genetic disorders that cause ASD will have an impact on how the brain functions, but the effects can vary widely from one person to the next, even within the same family.
This is why the behavioral diagnosis and the genetic diagnosis must go hand in hand. A positive genetic test result can only identify children at risk for having ASD.
Have a confirmed case of autism is vital because it can help the child in question receive certain school and therapeutic services and benefits.
Many parents falsely assume that a positive result from a genetic test alone means that their child already has autism. That’s not the case.
It means that the risk factor is present for the possible onset of autism which cannot be confirmed until the child has been formally evaluated from a behavioral standpoint. The two components go hand in hand.
Genetic tests alone are not intended to diagnose autism but their results can substantially alter the course of treatments or prevention. Some mutations reveal that the autism carrier is prone to medical conditions such as seizures, obesity or kidney problems, for example.
In addition, people with the same mutation can help advance research by sharing data and individual traits.
Knowing specific risks associated with a mutation also helps families make decisions about having more children.
Genetic testing for autism before pregnancy
At the present time, there is no test for pregnant or prospective mothers that can predict the probability of a child be diagnosed with autism.
However, recent estimates indicate that if a mother has previously had a child with autism, the risk of having a second child with autism is approximately 18.7 percent. This compares to the risk of autism in the general population of about 1.7 percent.
Gene sequencing can identify mutations linked to autism even if a child’s birth and other types of analyses already can detect fetal mutations. Some detect large DNA segments that are swapped between chromosomes, and others can pick up on missing or duplicated copies of DNA fragments.
There are new studies taking place that are among the first to scan for mutations across the entire fetal exome. Exome is the term used to refer to all the exons in the genome collectively.
However, these studies are initiating a number of ethical questions, including whether parents might choose to terminate a pregnancy based on the results. Researchers note that most of the mutations they found pose serious health risks, which could be treated at birth or in utero.
There are misconceptions that these tests are always done to decide whether or not to end a pregnancy. But clinicians stress that it is important to give information to families and physicians so they can plan for the whole pregnancy and the birth, and best identify the family’s needs and the baby’s needs.
Is genetic testing necessary if my child has already been diagnosed?
Yes. The behavioral diagnosis is strengthened by the genetic diagnosis. When combined, they form a more effective way to treat autism, especially since there are many possible permutations of the condition.
The diagnosis is simply a description of the condition that can be important for a number of reasons, but it does not answer the “why” that is the root cause of autism in that particular individual.
Genetic testing provides a new level of information that can be used to help more clearly define how to best monitor, treat and react to the various challenges of autism. Genetic testing provides a critical roadmap on how to treat someone going forward.
Who should have a genetic test for autism?
Persons who fall into one of the higher risk categories, couples contemplating having children for the first time, families where a child already has been diagnosed with autism, parents who are older, and children who already have been diagnosed with autism on a behavioral level are some of the primary targets for genetic testing for autism.
It might be best to start a conversation with your primary care physician to get their input if you have concerns about autism going forward.
What genetic test is right for my child?
There are several genetic tests available for children with ASD and other forms of childhood developmental delay.
It is probably best to meet with a genetic counselor to get more information based on the specifics of a child’s autism behavioral diagnosis. Having a specific diagnosis prevents unnecessary testing and with an informed prognosis or what to expect in the future can zero in on needed services, identifying underlying medical risks associated with a specific diagnosis.
The list of benefits of genetic testing for children with ASD or developmental delay is growing every day as new research emerges.
Once the test is done, how soon are results available?
Depending on the lab where the test is done, it could take anywhere from two to eight weeks for results.
Costs of genetic tests for autism
Depending on the specific type of autism test that is ordered, costs can range on the low end of about $1,000 and several thousand dollars on the high end.
Costs are often a barrier to testing because insurance companies don’t routinely reimburse for them. Their argument is that the results won’t change autism care.
Medical professionals often have to lobby for payment and find that reimbursement varies depending on the coverage a person has, the company they have it with and the individual screener they end up talking to about coverage.
In other cases, a child’s doctor can refer a child to a genetics team. A genetics team consists of a genetic counselor and a geneticist. This service is usually covered by insurance, just as referrals to other specialists are covered.
Genetic testing for therapy and treatment
Most genetic conditions do not have a specific cure or treatment, but there may be other benefits to having that information.
Knowing that a child has a particular genetic change may alert healthcare providers to test for other conditions that may go along with it.
For example, changes in SCN2A, a gene associated with autism, could influence the type of epilepsy medication the person takes.
Also, families may learn about what to expect in the future, if that information is available.
If a diagnosis is made related to genetics, there are generally support groups or organizations of other individuals with the same genetic change. It helps to be able to connect with those individuals or families to share information.
Some parents also want to know if they share their child’s genetic change, and whether they could pass it to other future children.
Ruling out genetics also means that focus can be redirected to environmental factors. This may include exposure to pollution, pesticides, and hazardous chemicals.
Other factors may include the age of parents when they conceive a child; a pregnant woman’s medical conditions (such as gestational diabetes and bleeding), illnesses and nutrition; and events that happen at and after a baby’s birth.
Genetic tests for autism strengths and limitations
Most researchers believe that a combination of several genetic differences, possibly combined with environmental factors, may lead to autism.
Because it is a spectrum disorder, autism can present itself in many ways. Scientists are still working to link various elements of the spectrum to genetics, and pieces are constantly being filled in as more data becomes available.
In general, people with ASD may have problems with social, emotional and communication skills (limitations). However, many people with ASD may also have heightened abilities in other areas (strengths).
Genetic testing will not reveal these limitations and strengths, but being armed with accurate information is still vital in the overall management of autism.
For example, Asperger’s Syndrome is a form of autism and a disorder characterized by significant difficulties in social interaction, along with restricted and repetitive patterns of behavior and interests. It differs from other ASDs in that those with Asperger’s possess developed linguistic, communication, and cognitive skills.
In fact, those with Asperger’s often have remarkable talents and are highly intelligent.
Children with autism spectrum disorder do not have a natural learning process. They cannot learn behaviors with their own experiences.
Many experts believe that this disorder can be rehabilitated, although it does not have a cure.
Because of this, imitation skills and role modeling are much more important for children with autism. For autistic children to be able to acquire certain behaviors, they need to imitate.
Children with autism struggle with understanding abstract information, but they can successfully imitate behavior they are shown during their learning process.
Determining what a child with autism is good at is important by providing him or her with a sense of achievement. The more they practice their skills or build upon their strengths, the happier and more successful they will become in their upcoming life.
Autistic people may display a range of strengths and abilities that can be directly related to their diagnosis, including:
- Learning to read at a very early age (known as hyperlexia).
- Memorizing and learning information quickly.
- Thinking and learning in a visual way.
- Logical thinking ability.
- May excel (if able) in academic areas such as science, engineering and mathematics as they are technical and logical subjects that do not heavily rely on social interaction.
- Having an extraordinarily good memory (being able to remember facts for a long period of time).
- Being precise and detail orientated.
- Exceptional honesty and reliability.
- Being dependable for schedules and routines.
- Having an excellent sense of direction.
- Be very punctual.
- Strong adherence to rules.
- Able to concentrate for long periods of time when motivated.
- A drive for perfection and order.
- A capability for alternate problem solving.
- A rare freshness and sense of wonderment.
On the opposite side, autistic children are challenged by:
- Hard time motivating
- Difficulty of focusing on something other than interest
- Following unwritten social rules; these rules can be learned through instructions
- Getting the big picture
- Unbalanced set of skills
- Difficulty with generalization concepts
- Having trouble expressing feelings in a way that other people would understand or expect
- Trouble with functioning, hence difficulties in planning long-term activities
- Perceiving emotions of other people
- Having trouble with summarizing information to include in speech
How accurate is genetic testing for autism?
Currently, genetic testing can only confirm that there has been a genetic mutation that can lead to autism in a person. However, researchers are continuing to make progress in linking genetic testing with a diagnosis of autism.
In 2012, a team of Australian scientists claimed that they had developed a genetic test that predicts a person’s risk of developing ASD with 72 percent accuracy. At the time, this claim was challenged, but it did point to ongoing research trying to find a more accurate way to diagnose autism through genetic means.
In 2018, researchers announced the findings of a new blood test that predicts autism with 92 percent accuracy. The scientists found an association between ASD and damage to some proteins found in the blood’s plasma, or the fluid that carries white and red blood cells.
Of the several blood and urine tests that the scientists developed, the most accurate one found that children with ASD had higher levels of a compound called dityrosine and another class of compounds called advanced glycation end-products (AGEs).
The overall control group was small, but the study points to the progress that is being made regarding genetic testing and autism. The goal is to achieve an earlier diagnosis so that earlier intervention strategies can be employed.