Assessing the Safety and Tolerability of NMN in DHDDS-CDG

Change in ICARS score from baseline to end of the treatment period (6 months) and long term follow up (12 months). The minimal score is 0 and the maximum score is 100, with a higher score indicating greater impairment as a result of ataxia.

Cord walking performance will be quantified using a standardized video-based computer vision pipeline applied to semi-structured recordings of participants walking along a straight line. Markerless pose estimation algorithms will extract time-resolved body keypoints, from which predefined gait and postural metrics will be derived, including step width variability, step length consistency, lateral deviation from the walking path, and trunk instability (e.g., standard deviation of body lean). Each metric will be summarized per recording and combined into a composite gait stability score using a prespecified algorithm. Change from baseline to 6 and 12 months will be calculated as within-subject differences in these quantitative measures, enabling objective assessment of gait abnormalities over time.

Archimedes spiral test performance will be quantified using standardized digital analysis of recorded spiral drawings. Video or image inputs will be processed to extract the drawn trajectory, and quantitative features of tremor and motor control will be computed, including line deviation from an ideal spiral template, tremor amplitude (spatial variability), frequency of oscillations, and drawing smoothness (e.g., velocity and jerk metrics). These features will be aggregated into a composite tremor severity score using a predefined scoring framework. Change from baseline to 6 and 12 months will be assessed as within-subject differences in these quantitative metrics, providing an objective measure of hand tremor severity and progression.