Abstract
Angelman syndrome (AS) is a rare neurogenetic disorder. Previous studies indicate a high prevalence of autism spectrum disorder (ASD) with considerable variability. Little is known regarding the longitudinal trajectory of autistic traits. We aim to investigate autistic traits, the effect of age on these traits, and associated features in AS children. This (partly) longitudinal clinical record study at the ENCORE Expertise Center involved 107 AS children aged 2-18 with one (N = 107), two (N = 49), or three (N = 14) measurements. Autistic traits and sensory processing issues were assessed using various instruments, and DSM classifications were used descriptively. Covariates were genotype, gender, and epilepsy. Results indicate a high prevalence of autistic traits and sensory processing issues. Children with the deletion genotype exhibited more autistic traits. Autism Diagnostic Observation Schedule (ADOS) classifications indicated higher rates of ASD compared to clinician DSM classifications. Autistic traits generally remained stable over time, except that ADOS scores significantly decreased for children with the UBE3A mutation genotype, and in the social affect domain for the entire group. In conclusion, incorporating the assessment of autistic traits and sensory processing into clinical practice for AS is important to inform adaptations of the environment to meet the child's needs. Additionally, clinicians and researchers should be mindful of the potential for overestimating ASD traits in AS when relying on the ADOS. ASD diagnosis in AS should integrate multiple diagnostic instruments, diverse hetero-anamnestic sources, and multidisciplinary expert opinions.