Autism Spectrum Disorder (Matoba, 2020) – Is autism genetic?

Nebula Genomics DNA Report for Autism

Is autism genetic? We created a DNA report based on a study that attempted to answer this question. Below you can see a SAMPLE DNA report. To get your personalized DNA report, purchase our Whole Genome Sequencing!

Is autism genetic? Sample report from Nebula Genomics.
Variants in an autism spectrum sample report
To learn more about how Nebula Genomics reports genetic variations in the table above, check out the Nebula Research Library Tutorial.
This information has been updated to reflect recent scientific research as of April 2021.

Introduction (Part 1 of Is autism genetic?)

Autism is a pervasive developmental disorder characterized by social communication and interaction challenges, along with restricted and repetitive patterns of behavior, interests, or activities. Before 2013, the disorder was divided into multiple subcategories such as Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS). In 2013, the name autism spectrum disorder (ASD) was adopted to describe the wide range of diverse autism phenotypes. It usually occurs before the age of three, and qualitative symptoms can be associated with a diagnosis of ASD, including:

  • Problems with social interaction and exchange (such as understanding and building relationships)
  • Conspicuousness in verbal and non-verbal communication (such as eye contact and body language)
  • Limited interests with repetitive, stereotypical behavior

People with ASD also have an increased risk of psychiatric problems such as anxiety, depression, obsessive-compulsive disorder, and eating disorders.

Is Autism a Genetic Disorder?

The genetic factors of the entire range of the autism spectrum are extremely diverse and highly complex, and thus no specific genetic influence is acknowledged. The genetic risk factors may be associated with environmental influences as well. So, is autism genetic or environmental? What are the environmental risk factors for autism?

There appears to be a significant genetic component as almost 20% of younger siblings of a child with ASD will receive a diagnosis themselves, higher than the CDC-reported 1% to 2% increased risk for autism among the general population.

Changes in over 1,000 genes have been reported to be associated with ASD, but a large number of these associations have not been confirmed. Many of the genes related to ASD are involved in the development of the brain. Some twin studies show that autism is a highly heritable condition and, as of 2009, known genetic syndromes, mutations, and metabolic diseases account for up to 20% of autism cases. It is generally assumed that the immense combination possibilities of many genotypes cause the great diversity and breadth of the autism spectrum.

Autism puzzle
Many genes associated with autism are involved in brain development. Pixabay.com.

The disorder may occur when mutations affect a single gene, mutations that impact multiple genes, multigene interactions, and/or epigenetics. It may also be associated with other disorders such as Fragile X Syndrome. According to the CDC, a national parent survey found that 46% of males and 16% of females with Fragile X Syndrome have been diagnosed or treated for ASD. Others have suggested that environmental factors combined with a genetic predisposition increase the risk factors for autism. 

Submicroscopic changes in chromosomes also play a key role, namely copy number variations. Chromosomal abnormalities most often happen in the form of gene duplication or gene deletion that occur when the mother’s eggs or the father’s sperm cells (meiosis) are formed. 

Diagram of gene deletion and duplication
Gene deletion (left) and duplication (right). Richard Wheeler (Zephyris) Attribution-Share Alike 3.0 Unported.

However, if a child receives such a deviation from one of the parents, it can be passed on, with a 50% probability. Thus, it is possible that an abnormality that contributes to autism occurs only once in a child and is not passed on, or it may affect several family members in different generations. The impact (penetrance and expressiveness) of such a genetic abnormality can also vary greatly from person to person.

Identical twins usually both have an autism spectrum disorder. Exceptions to this rule are attributed to environmental factors and epigenetic influences. Modern analytical methods (DNA chip technology) allow the detection of genetic abnormalities that lead to spectrum disorder expressions. The results can then form the basis of genetic consultations.

Current Research on Autism (Updated 2021)

Autism is an active area of research with over 6,000 articles and over 700 reviews catalogued in PubMed in 2020. 

In 2017, Sleep in Children with Autism Spectrum Disorder provided an overview of the relationship between sleep and children with ASD. 

Association of Genetic and Environmental Factors With Autism in a 5-Country Cohort is a study published in the journal JAMA Psychiatry in July 2019 that discovered that autism spectrum disorders are 80% caused by inherited genes. This is the largest study of its kind to date. 

Researchers are also investigating conditions that tend to be comorbid with the disorder. In 2020, there is some evidence to suggest CRISP technology may lessen symptoms of Angelman syndrome and that a type of gene therapy may curb deadly seizures in certain forms of epilepsy.

Spectrum, a division of the Simons Foundation Autism Research Initiative, continues to highlight new research, such as this recent study from April 2021 suggesting that progress in treatment shows a strong tendency to level off in many children at age 6.  

For more recent research, you can also check out Autism Speaks top 10 studies of 2020. Here, scientific staff and advisors summarize what they believe to be the most impactful autism studies of the year, including those that focus on interventions and health disparities. The United States Department of Health and Human Services (HHS) also shares recent research and resources.

Epidemiology updated 2020 (Part 4 of Is autism genetic?)

In 2020, the Centers for Disease Control and Prevention (CDC) reported that about 1 in 54 children had been identified with ASD, according to estimates from CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network made in 2016. ASD is reported in all racial, ethnic, and socioeconomic groups. It is more than four times more common in boys than in girls. The CDC is continuing funding for this initiative to run at least through 2024.  

Characteristics of Autism (Part 5 of Is autism genetic?)

The disorder may present itself in diverse ways. Symptoms can be mild to severe, with different levels of ability and disability.

Childhood autism

This is the most common form. According to autism research performed by the American Psychiatric Association, the most critical areas affected in children and adolescents are:

  1. Social interaction: A qualitative impairment of social interaction is sometimes already evident between 0 – 2 years due to a lack of contact with parents, especially the mother. Many children born with autism do not stretch out their arms to the mother to be lifted. They do not smile back when they are smiled at and do not make appropriate eye contact with the parents. Children also show a strong object-relatedness, often limited to a specific type of object. 
  1. Communication: About one in two children with early childhood autism does not develop spoken language. In the others, speech development is delayed. Most pronounced is the impairment of pragmatics: In communication with other people, autistic people have difficulties understanding what is said beyond the exact meaning of the word, in reading between the lines. Their voice often sounds monotonous (missing prosody). The children have an individually varying need for physical contact. Some take up direct and sometimes socially inappropriate contact with strangers, while for others, the sense of touch can be unpleasant for them due to this sense’s hypersensitivity.
  1. Repetitive and stereotypical behavior patterns: Changes in their environment worry and unsettle some autistic people. Sometimes they become upset when objects are no longer in their usual place or in a particular arrangement, or are distressed by an unannounced visit or spontaneous change of location. Actions are usually ritualized, and deviations from these rituals lead to chaos in the mind, because autistic people usually have no alternative strategies for unexpected changes in situations or processes.
Signs of childhood autism
Signs of childhood autism. MissLunaRose12. Attribution-Share Alike 4.0 International

High functioning autism 

If all symptoms of early childhood autism occur together with normal intelligence (an IQ of more than 70), children are often diagnosed with high-functioning autism (HFA). Diagnostically important here is especially the delayed child development of speech. Compared to Asperger syndrome, motor skills are usually significantly better.

Due to the delay in speech development, low-functioning early childhood autism (LFA) is often diagnosed first. However, normal speech development can then take place later. Therefore, many HFA patients are indistinguishable from Asperger’s patients as adults, but in most cases, the autistic symptoms remain much more pronounced than in Asperger syndrome. 

Asperger syndrome

Asperger syndrome (AS) is considered a mild form of autism and manifests itself from about the age of four. Although many behaviors make heavy demands on the social network of those affected, especially those of close acquaintances and family, there are not only negative aspects of Asperger’s. There are numerous reports about the simultaneous appearance of above-average intelligence.

Symptoms and Diagnosing ASD (Part 6 of Is autism genetic?)

Children are normally diagnosed between 18 months and 2 years of age. Diagnosis is based on communication and behavior, not cause or mechanism. Under The Diagnostic and Statistical Manual of Mental Disorders (DSM–5), to screen for autism, medical professionals should look for:

  1. Persistent deficits in social communication and interaction across multiple contexts
  2. Restricted, repetitive patterns of behavior, interests, or activities. 
  3. These deficits are present in early childhood, typically before age three
  4. These symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning.
  5. The disturbance must not be better accounted for by Rett syndrome, intellectual disability, or global developmental delay.

Sample signs and symptoms include lack of social or emotional reciprocity, stereotyped and repetitive use of language or idiosyncratic language and persistent preoccupation with unusual objects.

Treatment (Part 7 of Is autism genetic?)

Treatment is based on the individual development of each patient. The National Institutes of Health and the National Institute of Mental Health are actively conducting clinical studies that prevent, detect, or treat ASD. 

Behavioral Therapy

Behavioral therapy is a common strategy to treat autism. The aim is to reduce disturbing and inappropriate behavior such as excessive stereotypes or (auto)aggressive behavior on the one hand and to build up social and communicative skills on the other. It focuses on social skill development, especially at young ages, and the reduction of characteristic repetitive behaviors. In principle, this is done so that desired behavior is consistently and recognizably rewarded (positive reinforcement). Occupational and speech therapy are also helpful with some children.

Drug treatment

There is no drug treatment. However, drug treatment of accompanying conditions and symptoms, such as anxiety, depression, aggressiveness, or compulsions with antidepressants (such as SSRIs), antipsychotic drugs, stimulants, and mood stabilizers.

Prognosis (Part 8 of Is autism genetic?)

The disorder can significantly affect personality development, career opportunities, and social skills. The long-term course depends on the individual characteristics of each patient. There is currently no cure for autism. 

Many of the difficulties reported by autistic people can be avoided or reduced by adjusting their environment. For example, some people report a sensation of pain for certain sound frequencies. Such people are significantly better off in a low irritant environment. Finding or creating an autistically appropriate climate is, therefore, an essential goal.

Communication training for autistic people and their friends and relatives through specially trained teachers and educators can be helpful. An increasing number of schools, colleges, and employers specifically for autistic people demonstrate the success of having autistic people live in autism-friendly environments.

Autism awareness heart
Many people with autism ask for tolerance and acceptance. Pixabay.com

Manifestations of the disorder cover a broad spectrum. Many people do not want a “cure” because they see it as part of themselves and not as a disease that needs to be cured by health care. Many adults with mild autism have learned to cope with their environment. Instead of pathologizing, they often wish for tolerance and acceptance.

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