What could be the cause of autism?
To this day, scientists and researchers are still investigating the causes of autism spectrum disorder (ASD). After years of research and validation, it is clear that there is not a single factor that causes autism.
Causes and risk factors for autism
Is autism inherited? Studies have shown that children may have a genetic predisposition to autism. This means that genes inherited from their parents make it possible for them to develop autism. However, it is a misconception to think that autism is caused only by genes.
In most cases, genetic factors need to be triggered by environmental factors in order to develop an autism spectrum disorder. While we now know that there is no single cause of autism, it is also important to recognize the multiple risk factors that can lead to it.
Genetic causes of autism
It is said that people with certain genetic variants may develop autism. These genes are thought to affect brain development.
People with genetic disorders such as Fragile X syndrome are at high risk of developing autism. This syndrome that causes learning disabilities is one of the many genetic abnormalities that cause autism.
How many genes cause autism?
To date, scientists have identified 30 genes associated with the risk of developing autism. Most of these genes are responsible for brain growth.
Some of these genes are ARID1B, ASH1L, CHD2, CHD8, DYRK1A, POGZ, SHANK3, and SYNGAP1. For example, the SYNGAP1 gene is essential for nerve cells and their communication with the brain. It is responsible for the "wiring" of the brain.
However, after decades of scientific research, scientists have not been able to determine a genetic trait that every person with autism has.
Can autism be inherited?
Because some forms of autism are most likely caused by heredity, autism can be hereditary. For example, twins and siblings born a few years apart may both have autism.
This theory proved accurate after the first twin study in 1977 (Folstein & Rutter, 1977). The study involved 21 pairs of twins, of which 11 were identical twins and 10 were heterozygotic. Identical twins were found to have a 36% similarity in autism symptoms, while identical twins were found to have a 0% similarity.
The inheritance of autism
Due to the many important studies on siblings with autism, it is clear that it has a genetic relevance. More research is needed to answer questions about genes causing autism.
According to research, parents with a first child with autism have a 10% chance of having a second child with autism. This is called the recurrence rate, and parents with children with autism need to be aware of this possibility.
A recent study found that younger siblings of children with autism may also not have ASD but still exhibit autistic features.
A study conducted by John Constantino, MD, a professor of psychiatry and pediatrics at the University of Washington, titled "Genetic Epidemiology of Sibling Relapse and Autism," found that more than 26 percent of households had siblings who did not develop ASD but were diagnosed with other developmental disorders, particularly in language skills.