GM1 and GM2 Gangliosidosis PROspective Neurological Disease TrajectOry Study (PRONTO)

The study is a prospective longitudinal, multicentric decentralized trial which will be performed in children diagnosed with late infantile or juvenile onset of neurological disease of either GM1 or GM2 Gangliosidoses (Tay-Sachs or Sandhoff disease). The study anticipates to include a total of approximately 35 patients. A large set of neurological functions will be evaluated by rating scales used by physicians and questionnaires answered by parents. Digital tools will be used to support the study procedures with virtual visits.

Primary outcomes

• Change in the Gait 9-point item score of the Scale for Assessment and Rating of Ataxia (SARA) [0-4 years]: Score between 0 (better) and 8 (worse) points
• Change in the Speech 7-point item score of SARA [0-4 years]: Score between 0 (better) and 6 (worse) points

Other outcomes

• Change in scores of SARA items Stance (7-point), Sitting (5-point), Finger chase (5-point), Nose-finger test (5-point), Fast alternating hand movement (5-point), Heel-shin slide (5-point) and overall score. [0-4 years]: Stance score between 0 (better) and 6 (worse) points Sitting score between 0 (better) and 4 (worse) points Finger chase test score between 0 (better) and 4 (worse) points Nose-finger test score between 0 (better) and 4 (worse) points Fast alternating hand movements test score between 0 (better) and 4 (worse) points Heel-shin slide score between 0 (better) and 4 (worse) points
• Change in the total score of the Motor Function Measure-32 (MFM-32), and each of the 3 domains [0-4 years]: The scoring of each item uses a 4-point Likert scale - score between 0 (worse) and 3 (better)
• Change of Timed Up & Go [0-4 years]: Time a patient takes to rise from a chair, walk 3 meters, turn around 180°, walk back to the chair, and sit down while turning 180°
• Change in swallowing score [0-4 years]: Assessment of patient swallowing ability - score between 0 (better) and 5 (worse)
• Change in the overall composite score of the Vineland Adaptive Behavioral Scale (VABS) [0-4 years]: Rated on 0 (never performed),1, 2 (habitually performed) scale
• Change in BSFC-s score for each of the 10 items and overall score [0-4 years]: Rated on a 4-point scale with the values "strongly disagree", "disagree", "agree", and "strongly agree"
• Collection of seizures events, choking episodes, respiratory tract infections [0-4 years]: Gathering data about presence/absence and frequency of seizures, choking episodes, respiratory tract infections

Sex: All, ages: 2 Years to 20 Years

Inclusion Criteria:

* Genetically confirmed GM1 Gangliosidosis or genetically confirmed Tay-Sachs or Sandhoff disease
* Onset of neurological symptoms on or after the patient's first birthday
* Achieved 12-month developmental milestones at normal developmental time points as per Principal Investigator's judgement
* Abnormal gait and/or speech disturbance

Exclusion Criteria:

* Patients who have received (within 6 months before screening), are currently receiving or are planned to receive (within the following 6 months) gene therapy, stem cell transplantation, experimental drugs, or any drug, which, in the Investigator´s opinion, may (have) interfere(d) with disease progression