Mapping the shared and unique structural asymmetry abnormalities of young children with autism and developmental delay/intellectual disability with normative models and their multimodal cascade

To understand the neural mechanism of autism spectrum disorder (ASD) concurrent with developmental delay/intellectual disability (DD/ID), it is essential to comprehensively take genetic, brain, and behavioural measurements as a whole and focus on subjects at early age. However, such research is still lacking. Here, using the sMRI data of 1030 children under 8 years old, we employed developmental normative models to explore the atypical development of gray matter volume (GMV) asymmetry in individuals with ASD without DD/ID, ASD with DD/ID and DD/ID, and their associations with neurophysiological measures and transcription profiles. By computing the individual deviations from typical controls, we observed an ASD-specific abnormal GMV laterality pattern that was more rightwards in the inferior parietal cortex and precentral cortex and noted abnormal within-group heterogeneity in the temporal pole. Specifically, ASD with DD/ID children exhibited more regional abnormalities; ASD without DD/ID children showed higher within-group variability; while children with DD/ID showed no significant abnormalities. However, there were no significant differences among the three groups. The GMV laterality of ASD without DD/ID children was associated with ASD symptoms, whereas that of ASD with DD/ID children was associated with both ASD symptoms and verbal IQ. Last, the GMV laterality of the ASD with DD/ID, ASD without DD/ID, and DD/ID groups was associated with shared and unique gene expression profiles, but the associations of the latter two groups with intellectual genes showed opposite effects. Our findings illustrated the atypical development of regional structural lateralization in autistic children, which is associated with upstream genes and downstream behavioural performance. The differences and similarity between ASD and DD/ID additionally improve our standing to the neural mechanism of neurodevelopmental disorders comorbidity. ### Competing Interest Statement The authors have declared no competing interest.