Autism – is there a genetic test for autism?
Autism is a neurological developmental disorder characterized by difficulty in communication development and repetitive behaviors.
Today, autism is not referred to as an individual disease, but as a wide range of conditions called the autism spectrum disorder (or ASD), that relate to different levels of communication challenges and impairments.
Is autism hereditary / genetic?
Like many diseases, autism has a genetic basis that puts certain people at higher risk of autism.
However, autism is not a classic genetic disorder. There is no single gene mutation known to cause autism (apart from one exception – Rett syndrome). In addition, there is no specific genetic defect common to all people with autism that can be identified. There are several gene mutations that have been linked to a higher risk of autism.
Genetic factors related to autism
Although no specific gene mutation has been found to directly cause autism, and there are currently no prenatal tests for an early diagnosis (during or before the pregnancy), there is a strong genetic basis to autism. Researchers have noticed that autism and autistic spectrum traits tend to run in families.
There is a high risk of autism in identical twins – a risk linked to the genetic basis of autism. The chances of a child whose twin has autism to also develop the condition are 20 times higher than the average risk in general population.
Genetic studies meant to identify loci (specific areas in the DNA) that are linked to autism have indicated several “suspicious” risk genes – none of which are solely responsible for autism. Among these risk genes are MET, EN2, CNTNAP2. However, the biological mechanism that causes these genes’ aberrations and the link to autism have yet to be fully explained.
Certain language impairments may also be linked to other risk genes, that increase the risk of autism in the family. At this stage there is no practical implementation for genetic studies on autism, and there are no routine tests for an early diagnosis and prevention. There is no doubt that autism is linked to genetic, environmental, and etiological reasons that are yet to be found.
Signs and symptoms
What are the symptoms of autism? What do autism signs look like? Most people with autism are diagnosed during the first year of their lives, although diagnosis is sometimes delayed due to the level of autism and functional impairment.
Difficulties with social interaction, impaired understanding of social situations, difficulty in sharing emotions such as happiness, and restricted interests. In addition, they suffer from severe language impairments and their speech development is delayed. They are unable to develop social interactions appropriate to their age and mental condition.
In addition, people with autism often have repetitive behavior patterns and stereotypical movements. They have a tendency for strict, often unexplained, rituals and routines that play an important part in their lives.
People with autism may have narrow or restricted interests, and hypersensitivity to sensory stimuli (sometimes hyposensitivity or under-responsiveness). Some people with autism also have intellectual disabilities, but this is not necessarily always the case and the two conditions do not always co-occur.
Since autism is a spectrum, it is important to remember that impairments can manifest in a wide range of ways and severity levels. For instance, mild autism can refer to Asperger’s syndrome – people with Asperger’s have difficulty understanding social interactions and forming relationships but have high verbal abilities and a talent for language.
Since signs of autism only appear after early childhood and there are currently no tests for a definite diagnosis, autism can only be diagnosed after the condition develops through diagnostic criteria created by health organizations around the world.
There is no genetic screening test available before or during the pregnancy that can rule out autism in the fetus. There are also no such tests for newborns.
Recently there have been reports on certain tests, often with a low level of efficiency, that claim to be able to detect autism at only several months of age. These tests (such as eye-tracking tests or tests measuring the baby’s reaction to faces) are yet to be in wide clinical use today.