The CANinform natural history study is the first multinational effort to rigorously gather both retrospective and prospective data from this patient population. Data collection includes extraction of retrospective data from medical records of living and deceased patients, and collection of prospective, longitudinal data from living patients and their parent(s)/caregiver(s). Motor function assessments are performed remotely in the home via video or in the clinic by qualified study team members. Families will be invited to attend clinic visits and/or will be followed remotely by the clinical site for approximately 3 years.