Mitochondrial disease is a progressive, multi-system neurodegenerative illness with a highly variable clinical presentation. In this "Test in Focus" episode of the "Answers From the Lab" podcast, Linda Hasadsri, M.D., Ph.D., discusses how advanced testing through Mayo Clinic Laboratories can expedite diagnosis for the challenging condition.

“Mitochondrial patients, at least in the Mayo experience, have to wait an average of approximately 12 years before they finally receive a diagnosis,” Dr. Hasadsri says. “A number of mitochondriopathies are actually treatable, and a timely diagnosis can really change the entire clinical course for a patient and their family.”

Mayo Clinic Laboratories offers a full suite of biochemical and molecular testing for mitochondrial diseases under one roof. Our molecular tests utilize custom-designed sequencing reagents and employ a pioneering methodology known as droplet digital PCR to determine heteroplasmy.

“We are the first and only lab that I know of in the world that utilizes this technology for this purpose, and it’s the only methodology that is truly quantitative,” Dr. Hasadsri says. “Accurate and sensitive determination of heteroplasmy is incredibly important, not just diagnostically, but also for the clinical management and prognostication in these patients.”

Listen to learn more about how mitochondrial disease testing can accelerate diagnosis and provide patients and providers insight about disease progression and treatment options.

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10/19/22 Update: Mayo Clinic Laboratories test ids have shifted from the time of the recording, MITOT is now referred to as CMITO and MITON is now referred to as NMITO.

Testing

CMITO | Combined Mitochondrial Full Genome and Nuclear Gene Panel, Varies

Previously referred to as MITOT

Useful information

• Diagnosing mitochondrial disease that results from variants in either nuclear-encoded genes or the mitochondrial genome
• A second-tier test for patients in whom previous targeted gene variant analyses for specific mitochondrial disease-related genes were negative
• Identifying variants known to be associated with mitochondrial disease, allowing for predictive testing of at-risk family members

Specimen requirements

Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

Submit only 1 of the following specimens:

Specimen Type: Whole blood

• Container/Tube:
  • Preferred: Lavender top (EDTA) or yellow top (ACD)
  • Acceptable: Any anticoagulant
  • Specimen Volume: 3 mL
  • Collection Instructions:
    • Invert several times to mix blood.
    • Send specimen in original tube.
  • Specimen Stability Information: Ambient (preferred)/Refrigerated
  • Additional Information: To ensure minimum volume and concentration of DNA is met, the preferred volume of blood must be submitted. Testing may be canceled if DNA requirements are inadequate.

Specimen Type: Cultured fibroblasts

• Container/Tube: T-75 or T-25 flask
  • Specimen Volume: 1 Full T-75 or 2 full T-25 flasks
  • Specimen Stability Information: Ambient (preferred)/Refrigerated <24 hours
  • Collection Instructions: Submit confluent cultured fibroblast cells from a skin biopsy from another laboratory. Cultured cells from a prenatal specimen will not be accepted.
  • Additional Information: A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing. An additional 3 to 4 weeks is required to culture fibroblasts before genetic testing can occur.

Specimen Type: Skin biopsy

• Supplies: Fibroblast Biopsy Transport Media (T115)
  • Container/Tube: Sterile container with any standard cell culture media (eg, minimal essential media, RPMI 1640). The solution should be supplemented with 1% penicillin and streptomycin.
  • Specimen Volume: 4-mm punch
  • Specimen Stability Information: Refrigerated (preferred)/Ambient
  • Additional Information: A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing. An additional 3 to 4 weeks is required to culture fibroblasts before genetic testing can occur.

Performance information

• Report available: 28 to 42 days
• Day(s) and time(s) performed: Varies

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