Mitochondrial DNA Depletion Testing (Muscle)

Muscle | Extracted DNA from Muscle

Muscle: 50-75 milligrams muscle snap frozen in liquid nitrogen and maintained at -80°Celsius or below. Extracted DNA from muscle: Preferred quantity: 400 nanograms, Minimum quantity: 200 nanograms.

Sterile screw capped vial

Collect biopsy per established policy. Muscle: Samples should be shipped frozen in an insulated container with 5-7 lbs. dry ice, overnight. Extracted DNA: Should be shipped overnight at room temperature. If previously frozen, DNA can be shipped in an insulated container with wet or dry ice.

DNA - ship at room temperature after extraction; Muscle - ship in insulated container with 5-7 lbs of dry ice

Room Temperature: DNA - 30 days, Muscle - 0 days; Refrigerated: DNA - 30 days, Muscle - 0 days; Frozen: DNA - Indefinitely, Muscle - Indefinitely; Freeze/Thaw: None

Extracted DNA A260:A280 ratio of outside of 1.8-2.0 range; Thawed and/or fatty muscle sample; Insiffucient sample volume

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).

Real-time Quantitative PCR Analysis