Mitochondrial DNA Depletion Testing (Muscle)

CPT: 81479

Special Instructions

This assay is not currently available in New York state.


Expected Turnaround Time

14 - 28 days


Specimen Requirements


Specimen

Muscle; extracted DNA - muscle


Volume

200 ng of DNA or 75 mg muscle


Minimum Volume

100 ng of DNA or 50 mg muscle


Container

Sterile screw capped vial


Collection

Collect biopsy per established policy.


Storage Instructions

DNA: Ship at room temperature after extraction. Muscle: Ship in insulated container with 5-7 lbs of dry ice.


Stability Requirements

Temperature

Period

Room temperature

DNA: 30 days; Muscle: 0 days (stability provided by manufacturer or literature reference)

Refrigerated

DNA: 30 days; Muscle: 0 days (stability provided by manufacturer or literature reference)

Frozen

DNA: Indefinitely; Muscle: Indefinitely (stability provided by manufacturer or literature reference)


Causes for Rejection

Extracted DNA A260:A280 ratio outside of 1.8-2.0 range; frozen blood EDTA tube; thawed and/or fatty muscle sample


Test Details


Use

To diagnose the mitochondrial DNA depletion syndrome (MDS). The test is also useful in assessing variants of uncertain significance in nuclear DNA genes that cause MDS. MDS is a clinically heterogeneous group of mitochondrial disorders characterized by a reduction of the mtDNA copy number in affected tissues without mutations or rearrangements in the mtDNA. MDS is phenotypically heterogeneous, and can affect a specific organ or a combination of organs, with the main presentations described being either hepatocerebral (i.e. hepatic dysfunction, psychomotor delay), myopathic (i.e. hypotonia, muscle weakness, bulbar weakness), encephalomyopathic (i.e. hypotonia, muscle weakness, psychomotor delay) or neurogastrointestinal (i.e. gastrointestinal dysmotility, peripheral neuropathy). Additional phenotypes include fatal infantile lactic acidosis with methylmalonic aciduria, spastic ataxia (early-onset spastic ataxia-neuropathy syndrome), and Alpers syndrome (see these terms).


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

Real-time Quantitative PCR Analysis


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