Movement disorders affect nearly all individuals with Angelman syndrome (AS), with the most common concerns being spasticity, ataxia (as observed in the majority of ambulatory individuals), tremor, and muscle weakness. Clinically, over time, individuals may develop a crouched gait which can cause a progressive decline in mobility. Similar motor disorders are observed in Angelman syndrome rodent models; dysfunction on the rotarod and reduced activity have been consistently reported in AS rodents. Under this grant, this translational research will explore various aspects of gait across different age groups and will be assessed and compared from both a non-clinical (rodent) and clinical (human) perspective.
Current patient mobility tests such as the 6-minute walking test or the 4-stair climbing test are inaccurate, lack rigor and reproducibility because they are highly dependent on patient motivation at the time of assessment and are not granular enough to discover quality changes in gait over time. They represent a single time point evaluation in a controlled environment, where the patients must travel to be assessed. Functional assessments are often not representative of a skill set when a patient is in their own environment. In addition, there is associated anxiety in unfamiliar environments for both the patient and the caregiver. Knowing that an individual will perform most accurately in a familiar environment, utilizing a measure that can be applied in that setting is ideal.
Current mobility tests in humans and rodents can be inaccurate, or not translatable; therefore, improved motor-based outcomes that can be assessed across species for gross motor skills, fine motor skills, and gait quality, require further dedicated research and resources. Drs. Duis and Silverman have narrowed down and developed several outcome assessments that can be utilized in parallel across both rodents and humans. This grant focuses on various spatial and temporal aspects of gait as an outcome measure in both preclinical (rodent) and clinical (human) research models, and will assess how that changes across developmental ages.
This study will test the production and accuracy of sensor-based technology in individuals with AS across all genetic subtypes (deletion, UPD, ICD, UBE3A mutation), as well as AS rodents in relationship to gross and fine motor markers. Dr. Duis will recruit 40 individuals with AS for the clinical half of the study. Drs. Duis and Silverman will utilize cutting edge sensor-based technology such as DigiGATE, ActiMyo® (using wearable brace-anklets to collect a wide variety of motor metrics), gait laboratory assessments via treadmills and 3D motion, and Zeno walkway. Drs. Silverman and Duis will also identify spatial and temporal parameters in the Ube3a mouse and the FAST Ube3a rat model. The information developed through this grant will provide truly translational outcome measures to test therapeutics across age groups in both rodent and human, with the goal of expediating its utility for human clinical trials.
By increasing the number of relevant, innovative, in vivo functional outcome measures in our wheelhouse, we will create more opportunities for identifying and moving forward successful medical interventions where we have accurate ways to assess motor improvements over time.