Mitochondrial DNA Depletion Testing (Muscle)

Muscle; extracted DNA - muscle

Frozen muscle tissue or extracted DNA (from muscle only)

200 ng of DNA or 75 mg muscle

Muscle: 75 milligrams; or extracted DNA: contact MNG Genetic Services 844-664-8378 (844-MNGTEST)

Sterile screw capped vial

Muscle: sterile screw capped vial; or extracted DNA: contact MNG Genetic Services 844-664-8378 (844-MNGTEST)

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).

Diagnostic testing

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

This assay does not detect single nucleotide variants (SNVs), small indels and large deletions. False positive or false negative results may occur for reasons that include rare genetic variants that may affect the analysis, homologous regions, blood transfusions, bone marrow transplantation, tissue-specific heteroplasmy, mislabeled samples or erroneous representation of family relationships. Low levels of heteroplasmy may not be reliably detected. Interpretation of the clinical significance of gene variations is limited by information about the variant that is available at the time of reporting and by the quality and quantity of clinical information provided with the sample. The interpretation of the clinical significance of variants may change. 

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

Real-time Quantitative PCR Analysis

Real-time quantitative PCR analysis to identify mitochondrial depletion