Inclusion Criteria:  1. Clinically symptomatic male or female subjects of all ages (newborns included) with a CNM resulting from a documented mutation in the MTM1 or DNM2 gene. 2. A written, signed and dated informed consent must be provided to participate in the study. For subjects <18 years, consent of parent(s)/legal guardian(s) is required; informed assent can be obtained from the child according to local regulations. 3. Willing and able to comply with all protocol requirements and procedures.  Exclusion Criteria:  1. Participation in any other interventional study. Participation in a previous study should be completed at least 4 weeks before the first study visit. 2. Currently undergoing or has undergone previous gene therapy or other therapy for CNM. 3. Current or past abuse of alcohol or recreational/narcotic drugs (with the exception of caffeine and nicotine), which in the investigator's opinion would compromise the subject's safety and/or compliance with the study procedures. 4. Current or relevant history of physical or psychiatric illness, that would make the subject unlikely to comply with the study procedures. (Note: Subjects in a wheelchair are not to be excluded). 5. Subject is mentally incapacitated, or parent(s)/legally-authorized representative are legally incapacitated or have limited legal capacity, or have lack of mental capacity to fully understand the protocol requirements and complete all study required procedures.