Myotonic Dystrophy Type 1

The goal of this interventional study is to demonstrate the feasibility and tolerability of music and movement intervention for children with congenital DM1, while providing indications of its effectiveness in improving brain and heart symptoms of DM1. Additionally, information from the collection of biological samples and wearable devices (accelerometer, EEG headband and ECG chest strap) will be used to identify brain-heart biomarkers and outcome measures for use in future research and trials. Researchers will compare the results of physical and cognitive assessments for each participant to assessments from baseline after 10 weeks of weekly music sessions. Qualitative measures (questionnaires and focus groups) will inform the feasibility of this intervention for this population. The main questions this study aims to answer are: * Are weekly music education sessions feasible for children with DM1? * Are weekly music education sessions tolerable for children with DM1? Participants will: * Attend 45-minute-long music sessions once weekly for 10 weeks. * Attend two clinic visits for cognitive and physical assessments. * Provide blood, saliva, stool and urine samples. * Use wearabl