New Study Helps Explain Autism Subtypes

A new study that identifies four different subtypes of autism affirms what many experts — and parents — have long observed: the developmental disorder varies significantly from person to person. Or as the saying goes, “If you’ve met one autistic person, you’ve met one autistic person.”

Paige Kalika, D.O., a pediatric neurologist with the University of Miami Health System, works closely with children who have autism. She says the variety of symptoms and genetic traits she finds in her patients can range from the relatively mild to the more pronounced.

“This is why it’s called Autism Spectrum Disorder,” Dr. Kalika says. “We’ve known for some time that an autism diagnosis can represent multiple conditions bundled together with a lot of different symptoms. There can be a vast difference from one end of the spectrum to another.”

She lauds the new study as “the first of its kind to distinguish the complex disorder and confirm what so many of us understand about diagnosing and treating these children.”

Like the study authors, she believes that more research will lead to additional distinct autism subtypes. This process will help develop and apply interventions ranging from behavioral and educational therapies to medications.

The study, published in Nature Genetics, identifies four clinically and biologically distinct subtypes of the condition. Researchers looked at 230 traits — including repetitive behaviors, developmental milestones, and social interactions — of more than 5,000 autistic children who participated in an extensive cohort study called SPARK, which tracks genetic and clinical presentations in questionnaires filled out by their parents. The data collected was then plugged into a computational model that arranged the children together on a cluster of traits.

Each of the four subgroups carries its own different clinical, genetic, and biological profiles:

1. Social and Behavioral Challenges

This is the largest subtype, comprising 37% of the participants studied.  This group has higher rates of anxiety, depression and ADHD. These children also show higher levels of repetitive behaviors and difficulties with social communications, but these tend to be classified as “mild core autism traits.” Generally, they do not have noticeable developmental delays. The genetic variations of this cohort affect physical traits and behaviors that tend to become noticeable later in childhood.

2. Moderate Challenges

The second largest subgroup, making up 34 percent of study participants, didn’t have co-occurring psychiatric conditions such as depression and anxiety, and they tended to reach developmental milestones with their age group. They did exhibit core autism behaviors — repetitive behavior, sensory sensitivities, lack of social interest or intense interest, and challenges with conversation — but not as strongly as other groups.

3. Mixed ASD with Developmental Delay

Comprising 19% of study participants, this group didn’t exhibit anxiety, depression or disruptive behaviors, but they did have repetitive behaviors and social setting challenges. They also experienced delays in early developmental milestones. This subtype tends to have genetic variants that affect early brain development.

4. Broadly Affected

The smallest group of participants (10%) exhibited the most severe challenges in almost every category, including developmental delays, psychiatric conditions, repetitive behaviors, and social issues. This subtype also had the most “de novo” mutations. These kinds of mutations are not inherited from parents. Rather, they occur for the first time in a family and are caused by DNA replication errors or exposure to mutagens like radiation or chemical substances.

An estimated 1 in 31 children in the U.S. have been diagnosed with ASD by the age of eight, an increase from 1 in 36 in 2023, according to a 2025 Centers for Disease Control and Prevention report.

And while it occurs among all racial, ethnic, and socioeconomic groups, ASD is three times more common among boys than among girls. The study also shows that there’s been a shift in diagnoses, with minority kids (Asian, Black, and Hispanic) showing higher prevalence rates than white children. (Asian children have a prevalence rate of 3.82%, followed by Black children at 3.66%, and Hispanic children at 3.30%.)

Pediatric neurologists attribute the rise in cases to better awareness and more access to diagnostic services. Dr. Kalika says that the identification of subtypes could lead to improved diagnoses among adults. The study, she adds, looked only at children diagnosed by the age of 8 years old and missed those who are not diagnosed until later.

“I see so many people who are not diagnosed until they’re adults, when their own children are diagnosed,” she says.

Autism is believed to have many causes, and experts already know that genetics plays a strong role.

In fact, about 20 percent of ASD de novo cases can be traced back to genetics.

Other studies point to an overall genetic contribution that ranges from 40% to over 80%.

In addition to building another foundational brick in ASD research, the study’s findings will likely pave the path forward for more targeted treatments tailored to each group.

Knowing what to expect while raising a child with autism will also be helpful for parents as they plan for the future and work with schools to create proper accommodations.

Dr. Kalika expects a hopeful future in precision therapy that “will have devised a method to deliver a healthy gene” for those who have genetic variants or mutations.

“The idea,” she adds, “is to target treatment to what people need, and this goes a long way in helping us achieve that.”

Written by Ana Veciana-Suárez, a regular contributor to the University of Miami Health System. She is an acclaimed author and journalist who has worked for The Miami Herald, The Miami News, and The Palm Beach Post.

Tags: Autism Prevalence Statistics, Autism Spectrum Analysis, Dr. Paige Kalika, Genetic Autism Research, Pediatric Neurology Advances