Abstract

Abstract Pathogenic variants in the cohesin genes, NIPBL and SMC1A , both cause Cornelia de Lange syndrome (CdLS), a rare genetic disorder associated with developmental delay and intellectual disability. This study aimed to compare sleep behaviors across individuals with CdLS caused by a variant in NIPBL or SMC1A , and identify relationships between sleep and behavior functioning. A total of 31 caregivers of individuals with a variant in NIPBL ( N = 22) or SMC1A ( N = 9) completed questionnaires regarding their child's sleep behaviors, behavior regulation, attention, and autistic features (repetitive behaviors and social communication difficulties) as part of the Coordination of Rare Diseases (CoRDS) registry. Findings showed a trend of increased behavior regulation difficulties and repetitive behaviors in the NIPBL compared to the SMC1A participants. Both groups presented with a similar degree of attention, social communication, and sleep challenges. In the whole sample, sleep disturbance was strongly correlated with more behavior regulation difficulties, a relationship that was more robust in the NIPBL sample. In brief, study results support our prior observations of greater behavior difficulties among those with a variant in NIPBL as compared to SMC1A . Preliminary findings point to unique associations between sleep and behavior regulation in the NIPBL group, suggesting sleep interventions may yield differential effects on behavior management across variants.