Genetic Factors in Autism

Main Thing

Genetic factors significantly contribute to the development of Autism Spectrum Disorder (ASD).

Many different genes have been linked to autism, each contributing a small amount to the risk. Some of these genes are involved in brain development, while others affect how brain cells communicate with each other.Genetic factors in autism can be both inherited and new.

Inherited factors are passed down from parents to children, while new mutations occur spontaneously and are not present in the parents' genes.

Specific genes linked to autism have been identified.For instance, genes like SHANK3, CDH10, and MET have been associated with ASD. These genes play roles in synaptic development and the functioning of neural circuits, which are crucial for communication and social behavior.

Changes or mutations in these genes can disrupt normal brain development. This can lead to the behavioral and communication challenges seen in individuals with ASD.

An example of genetic influence is the presence of certain gene mutations in individuals with ASD that are not found in their neurotypical family members.

Terms

• Autism Spectrum Disorder (ASD) - A developmental disorder affecting communication and behavior. Example: A child diagnosed with ASD might have difficulties in social interactions and exhibit repetitive behaviors.

• Gene - A unit of heredity that contributes to a person's traits and health. Example: The SHANK3 gene is one of the genes that, when mutated, can contribute to ASD.

• Mutation - A change in a DNA sequence that can lead to differences in health and development. Example: A spontaneous mutation in the MET gene might increase the risk of developing ASD.

• Inherited Factors - Traits or conditions passed from parents to their children through genes. Example: If a parent carries a gene linked to ASD, it can be inherited by their child.

• Neural Circuits - Networks of neurons in the brain that work together to process information. Example: Disruptions in neural circuits due to genetic mutations can affect how a person with ASD perceives and interacts with the world.

An Analogy

Think of the human genome as a library full of books, which are the genes. In the case of Autism Spectrum Disorder, it's as if some of the books in this library have been edited or rearranged. These changes, or mutations, can affect the story that the genes tell - in this case, how the brain develops and functions.

A Main Misconception

A common misconception is that if a child has ASD, it must mean that the parents passed down the "autism genes". While it's true that genetic factors can be inherited, new mutations that were not present in the parents' genes can also contribute to ASD. For example, a child might develop ASD due to a new mutation in the SHANK3 gene, even if neither parent has this mutation.

The History

1. 1943: Autism is first described by Leo Kanner, but the genetic factors are not yet understood.

2. 1977: Twin studies suggest a genetic component to autism.

3. 1990s: The first gene mutations associated with autism are discovered.

4. 2000s: Advances in genetic technology lead to the identification of many more autism-associated genes.

5. 2021: Research continues to uncover the complex genetic factors in ASD.

As the geneticist Dr. Thomas Bourgeron said, "Autism is not a disease, it's a spectrum of disorders. And behind this spectrum, there is a spectrum of genes."

Three Cases How to Use it Right Now

1. A genetic counselor is advising a couple who are planning to have a child. One of them has a brother with ASD. The counselor explains the potential genetic risks and discusses options for prenatal genetic testing.

2. A neurologist is treating a child with ASD. Knowing that the child has a mutation in the SHANK3 gene, the neurologist considers targeted treatments that might address the specific neural circuit disruptions caused by this mutation.

3. A teacher is working with a student who has ASD. Understanding that ASD has a genetic basis can help the teacher to appreciate the student's unique challenges and strengths, and to advocate for appropriate supports and accommodations.

Interesting Facts

• More than 100 genes have been linked to ASD.

• ASD is about four times more common in boys than in girls, but the genetic reasons for this difference are still not fully understood.

• Some genetic mutations associated with ASD can also increase the risk of other conditions, such as epilepsy or intellectual disability.

• Even identical twins, who share 100% of their genes, do not always both have ASD. This suggests that non-genetic factors also play a role.

• Some of the genes associated with ASD are also involved in other psychiatric conditions, such as schizophrenia and bipolar disorder. This suggests that these different conditions might share some underlying genetic factors.