Motor impairments, neurological signs, and developmental level in individuals with Angelman syndrome.

The aim of this study was to examine the character of motor dysfunction in individuals with Angelman syndrome (AS). Thirty-three children and adolescents (median age 6 years, range 18 months to 23 years) were consecutively investigated for learning disability, epilepsy, and motor dysfunction to detect suspected AS. Twenty-three individuals (13 males, 10 females; median age 5 years 6 months, range 21 months to 23 years) fulfilled international consensus criteria for AS. Clinical diagnosis was supported by a positive DNA methylation test in eleven participants. Ten participants (seven males, three females; median age six years, range 18 months to 13 years) did not comply with consensus criteria for AS and were regarded as a comparison group. There was no significant difference between the AS and the comparison group regarding age or developmental level. Median developmental quotient level was 26 months (range 8 to 63 months); median gross motor developmental level in participants with AS was 24 months (range 8 to 60 months); median fine motor developmental level was 15 months (range 6 to 60 months). Muscle strength, spasticity, tremor, and coactivation were assessed: distal lower limb spasticity, ataxic like gait, stiff lower limbs, and the presence of coactivation during locomotion were significantly more frequent in participants with AS than in the comparison group (p<0.05). Asymmetry of muscle strength and spasticity were frequent. Neurological abnormalities were insufficient for a diagnosis of cerebral palsy and impeded function less than immaturity in both AS groups. Risk of increasing impairment needs to be anticipated to prevent negative long-term effects of muscle imbalance and motor asymmetries in individuals with AS.