Autism Research Suggests Distinct Genetic Profiles

January 29, 2026

New research has identified distinct genetic profiles linked to different behavioral and developmental patterns in autistic individuals, reinforcing the understanding that autism is highly complex and not driven by a single cause or influence.

In one study, researchers at the University of Cambridge discovered that individuals who were diagnosed with autism in early childhood, usually before age six, appeared to have a different genetic makeup and lower risk of developing co-occurring mental health conditions than did those who were diagnosed in late childhood and beyond.

Children with an early autism diagnosis were more likely to demonstrate challenges with social interactions from infancy to early childhood, the study showed. Children with a later diagnosis were more likely to experience social and behavioral struggles in adolescence, plus higher rates of comorbid ADHD, depression, PTSD, and self-harm. The study was published in October 2025 in the journal Nature.¹

“Understanding how the features of autism emerge not just in early childhood but later in childhood and adolescence could help us recognize, diagnose, and support autistic people of all ages,” senior study author Varun Warrier, Ph.D., assistant professor of neurodevelopmental research at Cambridge University’s Department of Psychiatry, said.

In a separate study from Princeton University and the Simons Foundation, researchers identified four clinically distinct subtypes of autism, setting the stage and establishing the potential for specialized care. They used data from more than 5,000 children to analyze combinations of traits, looking at social interactions, repetitive behaviors, and developmental milestones, rather than studying genetic links to single traits. The study was published in July 2025 in Nature Genetics.²

The four autism subtypes defined in the Princeton/Simons Foundation study included:

1. Social and Behavioral Challenges

Children in this group face more difficulties with social communication, attention, and repetitive and disruptive behaviors than do participants in other subtypes. This group also has the highest genetic predisposition for ADHD, anxiety, obsessive-compulsive disorder, and depression. Its members do not experience significant developmental delays.

2. Moderate Challenges

In this subtype, children exhibit traits that manifest as social challenges or stimming, but they usually reach developmental milestones at ages similar to their neurotypical peers. They generally do not experience co-occurring psychiatric conditions.

3. Mixed ASD and Developmental Delays

Gene variations identified in this subtype lead to early developmental challenges, as with walking and talking, in many, but not all, children. Members in this group tend to receive an autism diagnosis at an early age, and usually do not show signs of anxiety, depression, or disruptive behaviors.

4. Broadly Affected

Children in this subtype present with the most severe and wide-ranging difficulties, including ADHD, anxiety, depression, and mood dysregulation. The researchers observed impulsivity, hyperactivity, and aggressive behaviors only in this subtype.

Diagnosing Autism and Comorbid Conditions

In the University of Cambridge study, researchers analyzed genetic data from more than 45,000 autistic individuals in the U.S. and Europe, and behavioral data across childhood and adolescence from the U.K. and Australia. The team then linked the genetic data to the age at diagnosis, and found that the genetic profiles differed between those diagnosed with autism earlier vs. later in life, with only a modest overlap.

They also found that the average genetic profile of autism diagnosed later in life was closer to that of ADHD, and co-occurring disorders like depression and PTSD, than it was to autism diagnosed in early childhood. A lack of support in early childhood, however, may potentially increase the risk for mental health issues in the later-diagnosed group, the researchers pointed out.

“The presence of clear behavioral signs helps to facilitate diagnoses in younger children, but the umbrella of core features — social-communication differences and restricted interests and repetitive behaviors — can be more subtle and look different by age, sex, and sociocultural context,” says Gloria T. Han, Ph.D., assistant professor in the Department of Anesthesiology, Division of Pain Medicine, at Vanderbilt University Medical Center.

She says the Cambridge University study helps explain why some individuals, including females, children without language delays, and those who are highly verbal, are often identified later — sometimes after ADHD, anxiety, or other mood concerns are diagnosed. She says autism can be missed or overshadowed when differences in attention, executive functioning, or social difficulties are attributed only to ADHD or social anxiety.

Cambridge University’s Warrier summed up his research: “For the first time, we have found that earlier- and later-diagnosed autism have different underlying biological and developmental profiles. An important next step will be to understand the complex interaction between genetics and social factors that lead to poorer mental health outcomes among later-diagnosed autistic individuals.”

Carole Fleck is Editor-in-Chief at ADDitude magazine.

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