Asperger’s, now referred to as autism spectrum disorder (ASD), involves a complex interplay of genetic and environmental factors.

Asperger’s was once considered a distinct condition but is no longer an official diagnosis. Today, it is referred to as autism spectrum disorder (ASD) in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR).

ASD involves differences in social interaction, communication, and cognition. Some autistic people need no or minimal support, while others may need substantial support for their well-being and daily tasks.

Genetics plays a substantial role in autism. Environmental factors can also influence the expression of these genes, contributing to the chances of the condition.

ASD is considered to have a strong genetic component, with heritability estimated at 60–90%.

However, environmental factors can also influence its development. Recent evidence suggests environmental factors contribute to 40–50% of ASD variability.

ASD’s genetic makeup is complex. It involves a mix of genetic variations, both rare and common, that collectively increase the chance of the condition. Spontaneous mutations also contribute to this genetic aspect.

Furthermore, environmental factors are believed to play a role in the development of genetic mutations associated with ASD. These factors may include where you live, your diet, and infections during pregnancy.

ASD is a complex and highly diverse condition with no single “autism gene.” Instead, it’s believed to involve a combination of genetic and environmental factors.

Many genes have been implicated in ASD. Different autistic people may have variations in different genes.

In a 2022 study including more than 63,000 individuals, researchers analyzed various types of genetic mutations and identified 72 genes associated with ASD. They found that copy number variants (CNVs) had the strongest link to autism.

CNVs are a type of genetic variation that involves changes in the number of copies of specific sections of a person’s DNA. While most people have two copies of each gene (one inherited from each parent), CNVs can result in either fewer or more copies of a particular gene or DNA segment.

The same researchers conducted a meta-analysis including people with developmental delay. They found 373 genes associated with both ASD and developmental delay.

These genes were related to early stages of brain development in immature neurons. Some genes had different mutation frequencies between ASD and developmental delay groups.

This suggests that while common genetic pathways are involved in these conditions, there are also distinctions between them.

ASD isn’t exclusively linked to one particular parent. Both parents can contribute genetic factors for ASD, though recent research has shed light on potential parent-specific genetic influences.

For example, a 2019 study with more than 9,000 individuals from families with autism focused on rare genetic changes within non-coding areas of genes.

Findings indicated that when these genetic changes originated from fathers, they were more likely to be inherited by autistic children within the same family.

This suggests that specific, rare inherited genetic variations could heighten the likelihood of autism, with potential variations in chances depending on whether they are of maternal or paternal origin.

ASD is a complex condition. The following factors may increase the chances of having ASD:

Genetics

There’s a strong genetic component to ASD. According to a 2017 study, about 90% of the differences or variations in how ASD develops in autistic individuals can be explained by genetic factors.

Parental age

Children born to older parents, both mothers and fathers, have a slightly higher chance of ASD.

A five-country population study published in 2015 found that mothers 40–49 years old and fathers 50 years or older had a higher chance of having children with ASD than younger parents.

Additionally, mothers under age 20 were also associated with an increased chance of their offspring having ASD.

Premature birth

Premature birth and low birth weight may be associated with an increased chance of ASD. One 2020 study found that 22.6% of children born at 25 weeks received an ASD diagnosis, while the chance decreased to 6% for those born at 31 weeks.

Maternal prenatal factors

Maternal factors during pregnancy, including exposure to drugs, infections, or metabolic conditions, have been associated with a higher chance of ASD.

Research suggests that children whose mothers had prenatal infections had a 1.16 times higher chance of autism. Infections in the year before pregnancy were linked to a 1.25 times increased chance of autism.

Environmental factors

Exposure to environmental factors, like air pollution or pesticides, during pregnancy may have potential links to ASD.

A population 2022 study in Southern California found that exposure to fine particulate matter (PM2.5) during the first two trimesters of pregnancy was linked to an increased chance of ASD, with more pronounced effects in boys.

Asperger’s syndrome is no longer an official diagnosis. It is now included in the broader category of autism spectrum disorder (ASD).

ASD has a strong genetic component. However, environmental factors, such as parental age, maternal infection, and pollution, may also play a significant role.

Ultimately, autism is a complex condition shaped by multiple factors. Research is ongoing to better understand how it develops to improve early detection and support for those who need it.