Two genetic profiles are distinguished within autism associated with the age of diagnosis.
Science Editorial, Oct 1 (EFE).
What is known as autism is a spectrum of highly hereditary disorders, even in aspects such as the age of diagnosis. A study published this Wednesday in the journal Nature has identified two different genetic profiles associated with earlier and later diagnoses.
The work, the result of a broad international collaboration led by the Department of Psychiatry at the University of Cambridge in Britain, concludes that children diagnosed early, before the age of six, form a very different subgroup from those diagnosed later, and confirms that autism is not a single condition.
The genetic data come from more than 45,000 individuals across multiple cohorts in Europe and the United States, and the behavioral data come from smaller samples of between 89 and 188 autistic individuals per group, obtained through caregiver questionnaires on strengths and difficulties.
The findings indicate that children diagnosed with autism at a younger age (usually before age six) are more likely to display behavioral difficulties from early childhood, such as problems with social interaction.
Those diagnosed with autism later, in adolescence or beyond, are more likely to experience social and behavioral difficulties during adolescence and are more likely to suffer from mental health disorders, such as depression.
Investigating genetic characteristics based on age at diagnosis, scientists saw two very different profiles.
Closer to depression
They found that the average genetic profile of later-diagnosed autism is closer to that of Attention Deficit Hyperactivity Disorder (ADHD), Post-Traumatic Stress Disorder, and depression than that of autism diagnosed in early childhood.
This greater genetic overlap between autism diagnosed in adolescence and certain psychiatric disorders suggests, according to scientists, that there may be some genetic factors that increase the risk of mental disorders among people diagnosed with autism later in life.
Late diagnosis also means a greater lack of support in early childhood, which may contribute to the increased risk of mental health problems in the later-diagnosed group, as they are more vulnerable to bullying, among other issues, the researchers note.
The team also noted that commonly inherited genetic factors in these disorders influence the age at diagnosis, which may also be inherited.
“We’ve already discovered that early- and late-diagnosed autism have distinct biological and developmental profiles. The next step will be to understand the complex interplay between genetics and social factors that lead to poorer mental health among late-diagnosed autistic individuals,” says one of the authors, Varun Warrier, a researcher at the University of Cambridge.
“There are genetic influences that predispose people to display autistic traits from a very early age that can be more easily identified, leading to earlier diagnosis, while there are others that mean the traits don’t become evident until late childhood or adolescence,” Warrier adds.
“Understanding how the characteristics of autism emerge not only in early childhood, but also later, could help us better recognize, diagnose, and support autistic people of all ages,” he concludes.
