A decade-long UK study reveals that early severe infant epilepsy, particularly infantile spasms, may be a key pathway from genetic mutations to autism in children with tuberous sclerosis complex, highlighting early seizure management as crucial.
A long-running UK study has found that autism in tuberous sclerosis complex appears to be shaped by an early developmental chain linking inherited mutation, brain structure and severe infant epilepsy. Writing in the journal Epilepsia, researchers from the Tuberous Sclerosis 2000 Study followed children diagnosed with the genetic disorder for about a decade and found that almost 40% later met full criteria for autism, while a further 42% showed elevated autistic traits.
The analysis focused on mutations in the TSC1 and TSC2 genes, which disrupt mTOR signalling and are known to drive the brain abnormalities seen in tuberous sclerosis complex, including cortical tubers. By the time of the follow-up assessments, the study team had autism data for 86 participants and imaging data for most of the cohort. They reported that a higher tuber burden was associated with more severe autistic traits, but the relationship was not driven by where the tubers were located in the brain.
The clearest epilepsy signal came from infantile spasms, a severe seizure type that usually begins in infancy and is associated with poor developmental outcomes. Structural equation modelling suggested two indirect routes from genotype to autism: one through greater tuber burden and spasms, and another through spasms alone. More severe seizures at follow-up and lower IQ scores were also linked with higher autism scores, although once cognitive ability was taken into account, spasms remained the seizure feature most closely associated with autism.
The findings fit with earlier research showing that autism is far more common in tuberous sclerosis complex than in the general population. A 1998 PubMed-indexed study reported autism in 20% of a small TSC sample, while a later longitudinal study in the US found that 25% of 138 children had an autism diagnosis by 36 months. The TSC Alliance says prevalence in the condition is typically estimated at 41% to 69%, underlining why autism screening is routinely considered part of TSC care. The new study does not prove causation, but it strengthens the case that early epileptic activity, especially infantile spasms, may be a key part of the pathway from genetic vulnerability to later autistic traits.
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