Background Angelman syndrome (AS) is a rare, neurodevelopmental disorder which presents itself with severe cognitive and physical developmental delay. AS is characterized by frequent laughing and...Show moreBackground Angelman syndrome (AS) is a rare, neurodevelopmental disorder which presents itself with severe cognitive and physical developmental delay. AS is characterized by frequent laughing and smiling, but recent evidence suggests that individuals with AS, especially those with non-deletion genotypes, may experience high levels of anxiety. The aim of the current study was to examine the influence of genotype on anxiety and emotional/behavioral problems in general in Angelman syndrome (AS), and to test whether relationships between genotype and anxiety or emotional/behavioral problems were mediated by cognitive developmental level. Methods For this purpose, 79 children with AS were included from a Dutch clinical record study. The children were separated into two groups according to genotype, namely the deletion and non-deletion group (predictor). The Bayley Scales of Infant Development-III NL cognition subscale was used to measure cognitive developmental levels (mediator) and the Child Behavior Checklist (CBCL) was used to measure anxiety and emotional/behavioral problems in general (outcome). The study is cross-sectional in nature. A mediation analysis was performed, including four linear regression analyses. Results Genotype did not significantly predict anxiety levels (π½ = .18, p = .117) or emotional/behavioral problems (π½ = .06, p = .589). Genotype significantly predicted cognitive developmental level (π½ = .63, p < .001), as children with a non-deletion had a higher cognitive developmental level than children with a deletion. Cognitive developmental level neither predicted anxiety (π½ = .16, p = .155) nor emotional/behavioral problems in general significantly (π½ = .07, p = .554). Genotype did not significantly predict anxiety (π½ = .13, p = .387) or emotional/behavioral problems (π½ = .05, p = .746) with cognitive developmental level taken into account. This indicates that cognitive developmental level does not mediate the relationship between genotype and anxiety or emotional/behavioral problems. Key conclusions In conclusion, the findings of the current study suggest that emotional/behavioral problems, and specifically anxiety, are not affected by genotype or cognitive developmental level in children with AS. Therefore, the mediation model was not found to be significant. These findings may be taken to indicate that attention should be given to children of both genotype subgroups in clinical practice.Show less