Background: Angelman syndrome (AS) is a rare neurodevelopmental disorder affecting 1 in 15 000 to 1 in 24 000 individuals. The condition results in severe delays in development and expressive language and motor impairments. The Global Angelman Syndrome Registry was developed by families to facilitate longitudinal studies to advance research and therapeutics. This study describes preliminary clinical and behavioural outcomes.
Methods: Caregivers completed the Sleep Disturbance Scale for Children (SDSC; N = 161) and a 29‐item behavioural scale developed for Angelman Syndrome (N = 184). Relationships between seizure and gastroesophageal history, and behaviour and sleep were explored.
Results: A history of seizures was associated with higher levels of excessive somnolence (Mann–Whitney U = 2733.000, p = .028, d = .336), and greater incidences of spontaneous laughter/smiling (Mann–Whitney U = 3709.000, p = .009, d = .406), behaviour dysregulation (Mann–Whitney U = 3,550.000, p = .039, d = .318), and repetitive behaviours (Mann–Whitney U = 3566.000, p = .042, d = .305). A history of gastroesophageal reflux in infancy was associated with spontaneous laughter/smiling (Mann–Whitney U = 2973.500, p = .016, d = .377). Individuals with severe gastroesophageal reflux had higher levels of disordered breathing in sleep compared to individuals with mild cases (Kruskal–Wallis = 9.924, p = .007, d = .796). Medical treatment of gastroesophageal reflux was associated with higher levels of self‐injury (Mann–Whitney U = 913.000, p = .044, d = .388) and repetitive behaviours (Mann–Whitney U = 1003.000, p = .031, d = .454). Spontaneous laughter/smiling, anxiety and repetitive behaviours were associated with sleep disorders (Spearman's r range = .055–.361).
Conclusions: Repetitive behaviours, spontaneous laughter and self‐injury may represent seizure activity or efforts to communicate discomfort associated with gastroesophageal reflux. Excessive somnolence may be a side effect of seizure activity or anti‐epileptics, while disordered breathing may occur in sleep due to reflux.