Distinct Growth Characteristics in Angelman Syndrome

Objectives: Angelman syndrome (AS) is a rare, genetic, neurodevelopmental disorder characterized by severe impairments in speech, cognition and motor skills accompanied by unique behaviors, distinct facial features and high prevalence of epilepsy and sleep problems. Despite some reports of short stature among AS patients, this feature is not included in the clinical criteria defined in 2005. We investigated growth patterns among AS patients with respect to mutation type, growth periods, family history and endocrine abnormalities.

Methods: Data was collected from patients' medical files in AS national clinic. Mutation subtypes were divided to deletion and non-deletion. Four growth periods were defined: preschool, childhood, peak-height velocity, and final-height.

Results: The cohort included 88 individuals (46 males), with 54 (61.4%) carrying deletion subtype. A median of 3 observations per individual (range 1-10), produced 280 data points. Final-height-SDS was significantly lower compared to general population (-1.23±1.26, p<0.001), and in deletion group vs. non-deletion (-1.67±1.3 vs. -0.65±0.96, p=0.03). Final-height-SDS was significantly lower compared to height-SDS in preschool period (-1.32 vs -0.47, p=0.007). Patient's final-height-SDS was significantly lower than the parents' (∆final-height-SDS=0.94±0.99, p=0.002). IGF1-SDS was significantly decreased compared to general population (-0.55±1.61, p=0.04), with lower values among deletion group (-0.70±1.44, p=0.01).

Conclusion: AS patients demonstrate unique growth pattern with deceleration during childhood and adolescence resulting in significantly decreased final height compared to normal population, and even lower among deletion subgroup, which could be attributed to reduced IGF1 levels. We propose adding short stature to the clinical criteria and developing adjusted growth curves for AS population.
Keywords: Angelman syndrome, deletion, non-deletion, growth curves, IGF1