MITOCHONDRIAL DNA (mtDNA) CONTENT(qPCR) ANALYSIS
Muscle, skin, liver, or blood (test codes 3700, 3710, 3720, or 3730 respectively)

Description:

Mitochondrial DNA (mtDNA) Content Quantification determines if mtDNA depletion is present in the sampled tissue. The mtDNA content measurement, together with the clinical features, facilitates the selection of causative nuclear genes for sequence analysis.

Mitochondrial DNA depletion is a heterogeneous group of disorders characterized by the reduction of mtDNA content in affected tissues. Affected patients usually present in infancy with hypotonia, lactic acidemia, encephalopathy, hepatopathy, or myopathy. Mutations in at least 10 nuclear genes are known to cause various forms of mtDNA depletion syndromes, including severe infantile hepatic, hepatocerebral, myopathic, or encephalomyopathic forms.

Reasons for Referral:

Suspicion of mtDNA depletion syndrome

Testing Methodology:

The mtDNA and nuclear DNA (nDNA) contents are determined by real-time quantitative PCR using specific primers for the mitochondrial tRNALeu(uur) gene and the nuclear ß-2-microglobulin (ß2M) gene. The mtDNA copy number is calculated from the difference in threshold cycle numbers of mtDNA and nDNA.

Recommendations: We recommend ordering mtDNA Content Quantification with ETC enzyme analysis on muscle. If performed together, please send 100mg Muscle. Please read Muscle specimen requirements below.

Specimen Requirements:

Muscle (3700): 25mg. Muscle should be frozen rapidly after sampling. Do not add any liquid to the muscle and ship on dry ice by overnight carrier. If the muscle needs to be stored, keep at -80°C.
Cultured Skin Fibroblasts (3710) : DNA extracted from cultured skin fibroblasts or two T-25 culture flasks of one day post confluence. The flasks should be shipped at room temperature in an insulated container by overnight carrier.
Liver (3720): 25mg. Liver should be frozen rapidly after sampling. Do not add any liquid to the liver and ship on dry ice by overnight carrier. If the liver needs to be stored, keep at -80°C.
Blood (3730): EDTA (purple-top tubes: Adult: 14cc; Child: 6cc; Infant: 2-3cc

Turnaround Time:

3 weeks

CPT Codes and Prices:

Muscle: 83891x1, 83912x1, 83898x18, 83896x2
SFC: 83891x1, 83912x1, 83898x18, 83896x2
Liver: 83891x1, 83912x1, 83898x18, 83896x2
Blood: 83891x1, 83912x1, 83898x18, 83896x2

Shipping Information

Forms:

>> Mitochondrial Requisition - Mitochondrial Diagnostic Checklist is included

References:

1. Bai RK and Wong LC (2005). Simultaneous detection and quantification of mitochondrial DNA deletion(s), depletion, and over-replication in patients with mitochondrial disease. J. Mol. Diagn. 7(5): 613-622.

Test Codes:

Muscle: 3700
Cultured Skin Fibroblasts: 3710
Liver: 3720
Blood: 3730