Adaptive functioning in children and young adults with monogenic neurodevelopmental disorders.

Aim: To examine the adaptive behaviour profiles of children with monogenic neurodevelopmental disorders (NDDs) to determine whether syndrome-specific or transdiagnostic approaches provide a better understanding of the adaptive behavioural phenotypes of these NDDs.

Method: This cross-sectional study included parents and caregivers of 243 (48% female) individuals (age range = 1-25 years; mean = 8 years 10 months, SD = 5 years 8 months) with genetically confirmed monogenic NDDs (CDK13, DYRK1A, FOXP2, KAT6A, KANSL1, SETBP1, BRPF1, and DDX3X). Parents and caregivers completed the Vineland Adaptive Behavior Scales, Third Edition to assess communication, daily living, socialization, and motor skills.

Results: Linear regression models comparing mean adaptive behaviours between monogenic NDDs, adjusting for the presence of intellectual disability, revealed few group differences. Children with variants in BRPF1 or KANSL1 had better adaptive behaviour skills compared to children with variants in CDK13, DDX3X, DYRK1A, and KAT6A, although group differences varied across domains. A latent profile analysis showed compelling evidence for a five-profile model. These profiles were homogeneous, with similar delays across the subdomain scores in each profile. Additionally, each monogenic NDD was represented in each profile, with a few exceptions.

Interpretation: Transdiagnostic approaches to understand adaptive behaviour in monogenic NDDs provide a better understanding of individual strengths and challenges, enabling more targeted support.