autism genetic testing

Autism spectrum disorder is a developmental disorder usually characterized by difficulty in social interaction and communication and sometimes manifests as restricted or repetitive patterns of thought and behavior. Parents often search for signs of autism in their children as they develop, and most pediatrician offices give out questionnaires to screen children for autism. The definition of autism spectrum disorder has dramatically changed over the past 50 years, and is now seen on television shows, movies, websites, and in books. Publicly introducing individuals diagnosed with autism in recent years has made everyone more aware and acceptable of this disorder. 

 

The History of Autism Spectrum Disorder

In 1943, a physician named Leo Kanner started to observe a group of children who had been diagnosed with mental retardation but were not behaving in a typical fashion associated with mental retardation. He noticed that these children had difficulty in speech and social skills, and engaged in repetitive behaviors. These children did not like changes in their routines, and some of them lost skills they had learned over time. It was assumed that these children behaved this way because of their parents and how they raised their child, or rather lack of parenting, and were usually placed in institutions far from the public eye. 

Autism’s core symptoms are social communication challenges and restricted, repetitive behaviors. Symptoms of autism may begin in early childhood and interfere with daily living. Social communication challenges include difficulty with verbal and non-verbal communication such as spoken language, gestures, eye contact, or tone of voice. Restricted and repetitive behaviors include repetitive body movements and motions with objects, staring at lights or spinning objects, or narrow or extreme interests in specific topics. 

We now know that there is a wide range in severity and symptoms for individuals diagnosed with autism. The number of children diagnosed with autism has been increasing rapidly in the past few decades, but it’s unclear if that is due to an increase in the number of individuals affected by the disorder or the increasing knowledge and awareness of the disorder. As individuals are properly diagnosed with autism, we now know that autism affects almost five times as many males as females. 

 

Causes of Autism Spectrum Disorder

Autism is typically caused by a combination of genetics and environment. Studies have shown that changes in over 1,000 genes have been reported to be associated with autism, but many associations remain unconfirmed or have a clear, defined role in the disorder.  Many of the more well-defined gene associations with autism have also been found to only have a small effect in the overall disorder. However, approximately up to 40% of individuals with autism can have an identifiable genetic cause. Often the genetic cause is a chromosomal abnormality, which can mean a whole chromosome missing or duplicated, or a small piece of chromosome missing or duplicated. A genetic test called a microarray, which analyzes the chromosomes on a more detailed level, is considered the first-tier test to consider in individuals with autism, if a specific syndrome is not already suspected. 

 

Autism Genetic Testing

One of the most common inherited forms of autism is a syndrome called Fragile X syndrome. This condition is caused by a change in a gene called FMR1 and is passed on in an X-linked pattern, usually from mother to son. In addition to autism, individuals with Fragile X syndrome can have mild to moderate intellectual disability, seizures, long and narrow faces, unusually flexible fingers, flat feet, and in males, enlarged testicles after puberty. Prior to pregnancy or during pregnancy, women can have a blood test called carrier screening to be screened for their risk of carrying Fragile X syndrome and passing this condition on to a child. 

If you are interested in carrier screening or additional genetic tests, or if you have a personal or family history of autism, please contact AT-GC to speak with a genetic counselor and discuss genetic testing options.

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