Mitochondrial Genome Sequencing and Deletion Analysis

CPT: 81460; 81465

Test Includes

MT-ATP8, MT-ATP6, MT-CO1, MT-CO2, MT-CO3, MT-CYB, MT-ND1, MT-ND2, MT-ND3, MT-ND4L, MT-ND4, MT-ND5, MT-ND6, MT-RNR2, MT-TA, MT-TR, MT-TN, MT-TD, MT-TC, MT-TE, MT-TQ, MT-TG, MT-TH, MT-TI, MT-TL1, MT-TL2, MT-TK, MT-TM, MT-TF, MT-TP, MT-TS1, MT-TS2, MT-TT, MT-TW, MT-TY, MT-TV, MT-RNR1, MT-RNR2


Expected Turnaround Time

2 - 4 weeks


Specimen Requirements


Specimen

Whole blood, oral swab, cultured fibroblasts, muscle, extracted DNA


Volume

4 mL blood, 1 buccal swab, 2 T-25 flasks cultured cells, 75 milligrams muscle, or 1 microgram DNA A260:A280 ratio of 1.8-2.0


Minimum Volume

2 mL blood, 1 buccal swab, 1 T-25 flask cultured cells, 50 milligrams muscle, or 800 nanograms DNA A260:A280 ratio of 1.8-2.0


Container

Whole blood: lavender-top (EDTA) tube; oral swab: OCD-100 DNA Genotek device only; cultured cells: T-25 flask tissue; extracted DNA: sterile screw capped vial


Collection

Draw blood into EDTA tube. Collect swab specimen per guidelines in Labcorp kit. Transfer extracted DNA into sterile screw capped tube. Collect biopsy and/or culture cells per established policy.


Storage Instructions

Blood: Ship ASAP, but stable up to 5 days post-collection at room temperature. Do not freeze. Swab: 60 day post-collection room temperature stability; DNA: Ship at room temperature after extraction. Fibroblast: Ship flask in insulated container at room temp or refrigerated. Muscle: Ship in insulated container with 5 to 7 pounds of dry ice.


Stability Requirements

• Room temperature: Blood: 5 days; Swab: 60 days; DNA: 30 days; Muscle: 0 days; Fibroblasts: 2 - 3 days

• Refrigerated: Blood: 5 days; Swab: 60 days; DNA: 30 days; Muscle: 0 days; Fibroblasts: 2 - 3 days

• Frozen: Blood: Do not freeze; Swab: 60 days; DNA: Indefinitely; Muscle: Indefinitely; Fibroblasts: Indefinitely


Causes for Rejection

Frozen blood EDTA tube; insufficient swab cell collection or incorrect oral swab device use; thawed and/or fatty muscle sample; extracted DNA A260:A280 ratio outside of 1.8-2.0 range.


Test Details


Use

This test is used to diagnose mitochondrial disease that is caused by point mutations, small deletions/duplications or large deletions in the mitochondrial DNA (mtDNA). The test is also useful in assessing variants of uncertain significance in nuclear DNA genes that cause mtDNA deletion syndromes. While some disorders caused by mtDNA mutations only affect a single organ (e.g. the eye in Leber hereditary optic neuropathy [LHON]), many involve multiple organ systems and often present with prominent neurologic and myopathic features. Mitochondrial disorders may present at any age. Many individuals with mitochondrial disorders display a cluster of clinical features that into a discrete clinical syndrome, such as the Kearns-Sayre syndrome (KSS), chronic progressive external ophthaloplegia (CPEO), mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), myoclonic epilepsy with ragged fibers (MERRF), neurogenic weakness with ataxia and retinitis pigmentosa (NARP), or Leigh syndrome (LS). However, considerable clinical variability exists and many individuals do not fit neatly into one particular category, which is well-illustrated by the overlapping spectrum of disease phenotypes. Mitochondrial DNA deletion syndromes predominately comprise three overlapping phenotypes that are usually simplex (i.e., a single occurrence in a family), but rarely may observed in different members of the same family or may evolve in a given individual over time. Inheritance of mitochondrial DNA deletion syndromes can be either autosomal recessive (with progressive external ophthalmoplegia [PEO] and multisystem involvement manifesting during early childhood/adulthood), or autosomal dominant (with less severe, often tissue-specific manifestations [e.g., chronic PEO] developing in later adulthood).


Limitations

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.


Methodology

Next-Generation Sequencing


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