Genetics and autism diagnosis: The timing of an autism diagnosis may be partly influenced by genetics, with distinct developmental “trajectories” linked to different sets of common genetic variants, according to new research.
Analysing records of children diagnosed between the ages of 5 and 17, a Cambridge-led team found two broad patterns: one group showed early-emerging difficulties that remained relatively stable; another had fewer early issues but more challenges in late childhood and early adolescence. These trajectories accounted for an estimated 10–25% of the variation in age at diagnosis.
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Commonly cited factors such as sex and socioeconomic status had comparatively small effects, each explaining under 10% of the variance, the researchers reported. Genetic profiling suggested that children diagnosed later tended to carry a different constellation of common variants than those identified earlier, together explaining approximately 11% of the variation in diagnosis timing.
The findings add weight to the view that autism is not a single condition, but a spectrum comprising multiple subtypes with differing developmental courses and biology. “This really provides support for the idea that autism is actually potentially multiple conditions,” said Natalie Sauerwald of the Flatiron Institute in New York, who was not involved in the study. Lead author Varun Warrier of the University of Cambridge emphasised that the two groups exist on a gradient rather than as sharply divided categories and should not be labelled “milder” or “more severe.”
Children diagnosed later were also more likely to carry common variants associated with other neuropsychiatric conditions, including ADHD and post-traumatic stress disorder, an overlap noted in prior work and still poorly understood, researchers said.
