Trial Readiness and Endpoint Assessment in Pediatric Myotonic Dystrophy Extension

Primary outcomes

1. Change in ambulation over 24 months as measured by the 10-Meter Walk/Run Test (10M WRT)

   Time frame: Baseline, Month 12 and Month 24 visits

   The participant will be timed walking or running along a 10-meter course. It is scored by recording the total time taken to ambulate 6 meters (m) is recorded to the nearest hundredth of a second. 6 m is then divided by the total time (in seconds) taken to ambulate and recorded in m/s.

2. Change in mobility (100-meter timed test)

   Time frame: Baseline, Month 12 and Month 24 visits

   Mobility will be measured using the 100 Meter Timed Test (100m) in which the participant is asked to complete 2 laps around 2 cones set 25 meters apart as quickly as safely possible, running if able. The total time in seconds is recorded from when the participant starts walking until they break the plane of the 100 meter mark (i.e., when any part of the body passes the 100 meter mark).

3. Change in Time to Stand (SUPINE TO STAND test)

   Time frame: Baseline, Month 12 and Month 24 visits

   Participant will be timed transitioning from a supine position to standing. The participant will complete one trial of this test. The test measures the participant's ability to quickly rise from a supine position on the floor with arms at their sides, to full upright posture with arms at their sides. This should be performed without external support from another person, a device, or furniture. Results will be reported in seconds.

4. Change in Gross Motor Function (GMFM-88)

   Time frame: Baseline, Month 12 and Month 24 visits

   The Gross Motor Function Measure (GMFM-88) is an assessment tool originally designed and evaluated to measure changes in gross motor function over time or with intervention in children with cerebral palsy. The GMFM assesses functional abilities including; lying/rolling, sitting, crawling/kneeling, standing, and walking/running/jumping. A four-point ordinal scale of measurement is used to assess each item, higher scores denote better performance. A score of 4 on an item indicates a consistently normal response, a score > 4 indicates persistent hypertonus, and a score < 4 indicates various degrees of hypotonus.

5. Change in Handheld Dynamometry and Grip HAND-HELD DYNAMOMETRY (HHD)

   Time frame: Baseline, Month 12 and Month 24 visits

   Maximum hand and grip strength will be assessed using a myometer. The participant will be asked to squeeze a handheld tool. When performing a hand-held dynamometry (HHD) test, you generally want a high score as it indicates greater muscle strength in the tested area; a higher number signifies a stronger muscle contraction.

6. 9-HOLE PEGBOARD TEST (9HPT)

   Time frame: Baseline, Month 12 and Month 24 visits

   The Nine-Hole Peg Test (9-HPT) is a standardized, quantitative assessment used to measure finger dexterity. Test is measured in seconds.

7. VIDEO HAND OPENING TIME (vHOT)

   Time frame: Baseline, Month 12 and Month 24 visits

   . The participant will squeeze the hand for three seconds then open the hand as quickly as possible. A video recording of the procedure will be obtained showing the forearm and hand but not the face. Recordings will later be assessed by a blinded reviewer to determine the hand opening time. The time is recorded in seconds.

8. IOWA PERFORMANCE INSTRUMENT (IOPI)

   Time frame: Baseline, Month 12 and Month 24 visits

   The IOPI consists of a pressure bulb attached to a manometer. The pressure bulb will be placed on the participant's tongue. Participants are asked to push the bulb against the hard palate on the alveolar ridge just behind the upper central incisors for 3-5 seconds. This test should be repeated 3 times with a 30-second interval between trials. The maximum pressure is recorded.

9. CLINICAL EVALUATION OF LANGUAGE FUNDAMENTALS, 5th edition (CELF-5)

   Time frame: Baseline, Month 12 and Month 24 visits

   The mean score is 100, with a standard deviation of 15, meaning that standard scores between 85-115 are within the normal range. You can calculate the level of severity for delayed skills according to how many deviations below the mean a client's score is: Mild: 70-85, Moderate 55-70 , Severe: 55 and lower.

10. TIMED WATER SWALLOW TEST (TWST)

    Time frame: Baseline, Month 12 and Month 24 visits

    Participants will be given 3 ounces (90 mL) of water to drink from a clear cup. Safety of completing this test will be determined by the site PI with input from the parents/caregivers. Participants will be asked to drink the water as they normally would, without interruption. Straws may be used, if that is preferred. Participants will be asked to say aloud "I'm done" when they feel they've completed the task with a written cue provided as a reminder.26,27 Testing will be recorded for later quantification of time needed for test, volume ingested, volume/swallow, time/swallow, and swallow capacity (mL/swallow).

11. DOMAIN DELTA QUESTIONNAIRE

    Time frame: Baseline, Month 12 and Month 24 visits

    A "domain delta questionnaire" is a patient-reported questionnaire used in clinical research to assess how much a patient perceives their health status has changed across specific domains (like mobility, overall health, or upper limb function) between two points in time, essentially asking them if they feel they have gotten better, worse, or stayed the same in each area compared to a baseline measurement; it's a way to measure perceived change in health related quality of life over time.

12. INTELLIGIBILITY IN CONTEXT SCALE (ICS)

    Time frame: Baseline, Month 12 and Month 24 visits

    The ICS is a brief, 7-question, caregiver proxy instrument that rates relative intelligibility of a child with a variety of familiar and unfamiliar communication partners. It uses a 5-point Likert scale to rate the approximate level of intelligibility. ICS scores indicate a child's level of functional intelligibility, ranging from a score of 1.00 (low intelligibility) to a score of 5.00 (high intelligibility). If a child achieves an average score of 3.5, then it may be appropriate to indicate that the child is usually to sometimes understood.

13. PEDIATRIC QUALITY OF LIFE (PEDS QL) - GENERIC CORE SCALES

    Time frame: Baseline, Month 12 and Month 24 visits

    The PedsQL evaluates a child's health-related quality of life (HRQoL) with respect to social, emotional, physical, and school functioning. he PedsQL 4.0 Generic Core Scales consist of four scales measuring HRQoL in four domains: Physical, Emotional, Social, and School functioning. Scores of 81 or higher on the PedsQL™ SCD pain scales should be considered good HRQL functioning. These children likely have had less pain that was less severe than children with lower scores and/or are managing their symptoms well.

14. PEDIATRIC DAYTIME SLEEPINESS SCALE (PDSS)

    Time frame: Baseline, Month 12 and Month 24 visits

    SS is an 8-item scale that assesses daytime sleepiness in children as a PRO that has been used in sleep disordered breathing and epilepsy studies. 5 points Likert scale (0-4) for 8 questions concerning to sleepiness. Higher scores on PDSS were associated with reduced total sleep time, poorer school achievement, poorer anger control, and frequent illness.

15. BEHAVIOR RATING INVENTORY OF EXECUTIVE FUNCTION -2 (BRIEF2)

    Time frame: Baseline, Month 12 and Month 24 visits

    The BRIEF2 gives you the information you need to help children and adolescents with executive dysfunction. It digs deeper than similar measures and pinpoints exactly where and why children struggle, so therapists and schools can make informed and impactful intervention and accommodation recommendations. For all BRIEF2 clinical scales and indexes, T scores from 60 to 64 are considered mildly elevated, and T scores from 65 to 69 are considered potentially clinically elevated. T scores at or above 70 are considered clinically elevated.

16. VINELAND ADAPTIVE BEHAVIOR SCALES THIRD EDITION (VINELAND-3)

    Time frame: Baseline, Month 12 and Month 24 visits

    Vineland Adaptive Behavior Scales 3rd Edition is a leading instrument for diagnosing intellectual and developmental disabilities, providing valuable information for educational and treatment plans. Higher Internalizing and Externalizing v-scale scores indicate more problem behavior. If qualitative descriptors are desired, scores of 1 to 17 may be considered Average, 18 to 20 Elevated, and 21 to 24 Clinically Significant.

17. WECHSLER INTELLIGENCE SCALE FOR CHILDREN (WISC-V)

    Time frame: Baseline, Month 12 and Month 24 visits

    Wechsler Intelligence Scale for Children (WISC-V) is an intelligence test that measures a child's intellectual ability and 5 cognitive domains that impact performance. Low Average: 80-89. Students who test in this range may struggle to keep up in school, but are not generally eligible for special education or assistance. Average: 90-109. Students who test in this range are average and may or may not struggle to keep up in school.

18. AUTISM SPECTRUM SCREENING QUESTIONNAIRE (ASSQ)

    Time frame: Baseline, Month 12 and Month 24 visits

    Results consist of a total score between 0 and 54, where higher scores indicate that many characteristics of ASD were reported. A score of 13 and above indicates ASD is probable, with a true positive rate of 90% and a false positive rate of 22%.

19. REPETITIVE BEHAVIOR SCALE - REVISED (RBS-R)

    Time frame: Baseline, Month 12 and Month 24 visits

    The RBS-R is a questionnaire that focuses exclusively on RRBs. It includes 43 items rated on a four-point Likert scale: 0=behavior does not occur; 1=behavior occurs and is a mild problem; 2=behavior occurs and is a moderate problem; and 3=behavior occurs and is a severe problem.