Motor Outcomes to Validate Evaluations in Pediatric FSHD (MOVE Peds)

The primary goal of this study is to validate motor and functional outcomes and refine clinical trial strategies for pediatric-onset FSHD

MOVE Peds is a prospective 2-year study recruiting eighty pediatric participants to accelerate therapeutic development for pediatric-onset FSHD. The study aims to validate outcomes and refine clinical trial strategies. Previous cross-sectional studies suggest that younger age of onset is linked to greater clinical severity and that having 1-3 D4Z4 repeats is associated with extra-muscular complications in pediatric FSHD. Prospective studies in early-onset FSHD have been limited by the small number of sites and low recruitment and follow-up rates. Early-onset pediatric FSHD is of high interest to drug companies because: 1. It results in a more significant disease burden than in adults. 2. Treating FSHD at earlier ages may have a more lasting and profound effect. 3. Genetic, molecular, and clinical factors may differ between pediatric and adult-onset FSHD. 4. Smaller body size and faster progression rates may make AAV-delivered gene therapies more feasible. The FSHD CTRN's previous research showed that the FSHD composite functional measure (FSHD-COM), reachable workspace (RWS), and quantitative MRI measures (qMRI) are responsive to disease progression or treatment in adults with FSHD and correlate with performance. Investigators hypothesize that early changes in qMRI in pediatric subjects will predict 2-year changes in FSHD-COM Peds or RWS.

Inclusion Criteria: * Age 5-17 years. * Genetically confirmed FSHD (types 1 or 2). * Symptomatic weakness (facial, shoulder, core, or limb weakness) * Able to complete a 10-meter walk without the support of another person in less than 12 seconds (canes, walking sticks, and braces allowed; no walker). In order to include early onset participants up to 8 individuals will be entered with baseline 10MWR \> 12 seconds or who are no longer ambulatory (≤10%) Exclusion Criteria: * Unwilling or unable to provide informed consent or assent. Any other medical condition which in the opinion of the investigator would interfere with study participation. * Malignancy with ongoing treatment with chemotherapeutic agents or anabolic agents * Use of immunosuppressants including prednisone or performance enhancing drugs including testosterone within 6 months * Pregnancy * Recent or ongoing infection * Presence of contraindication to performance of MRI: pacemaker, metallic foreign body in eye, brain aneurysm clip (unless documented as MRI compatible) * In the opinion of the investigator unable to follow directions for standardized testing * Note: Not being able to complete MRI will not result in a screen failure. If subject is not able to complete the procedure due to fear or anxiety, they will have the opportunity to try again at later visits. However, Subject must be willing to attempt to perform the MRI to meet inclusion/exclusion criteria