The purpose of this study is to learn about the use of nutritional supplements in patients with mitochondrial disease.

Our goal is to better assess which nutritional supplements are prescribed to patients with mitochondrial disorders, the monitoring obtained and whether any subjective improvements are noted by the patients or their caregivers.

Inclusion Criteria:

• NAMDC Clinical Registry or RDCRN Contact Registry participant
• Diagnosis of a mitochondrial disease confirmed by either electron transport chain abnormalities or molecular testing.

Exclusion Criteria:

• Lack of participation in NAMDC or RDCRN registries
• Diagnosis of mitochondrial disorder not confirmed by ETC studies or molecular diagnosis

Participants will be recruited through the NAMDC Clinical Registry and RDCRN Contact Registry. Additional means of recruitment may be used to direct patients to join the NAMDC or RDCRN registries.