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Mitochondrial DNA Deletion Analysis

CPT: 81465

Specimen Requirements


Specimen

Blood | Extracted DNA | Cultured Fibroblasts | Muscle | Buccal Cells

Volume

Blood: Draw blood in a lavender top EDTA tube, Sample Stability: 5-7 days, Preferred volume: 4 ml, Minimum volume: 2 ml, DO NOT FREEZE. Extracted DNA: From leukocytes, muscle, or fibroblasts: Preferred quantity: 1 microgram, Minimum quantity: 800 nanograms. Genomic DNA should be eluted in sterile Dnase/Rnase free water or TE. The A260:A280 ratio should be 1.8-2.0. Cultured Fibroblasts: Two T-25 flasks of fibroblasts, preferably ~90% confluent. Muscle: 50-75 milligrams muscle snap frozen in liquid nitrogen and maintained at -80┬░Celsius or below. Buccal Cells: One buccal swab should be used for collection. Do not discard solution in collection tube; follow collection instructions supplied. Stability at ambient temperature is 60 days.

Container

Blood: Lavender-Top (EDTA) Tube, Buccal Swab from MNG Kit, Tissue or Extracted DNA: Sterile screw capped vial, Cultured cells: T25 flask

Collection

Blood: Specimens should be shipped overnight in a secure container at room temperature. 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. Cultured Fibroblasts: T-25 flasks containing fibroblasts should be shipped in an insulated container at room temperature. Flasks should be completely filled with media and cells should be ~90% confluent. Fibroblast samples must be certified free from Mycoplasma. MNG is able to perform this service for a small charge (TC05). For NGS panels, TAT will be extended by 7-14 days if cells are not confluent upon arrival. Muscle: Samples should be shipped frozen in an insulated container with 5-7 lbs. dry ice, overnight. Buccal cells: Should be shipped overnight in a secure container at room temperature.

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; Fibroblasts - ship flask in insulated container at room temp or refigerated; Muscle - ship in insulated container with 5-7 lbs 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; Freeze/Thaw: None

Causes for Rejection

Extracted DNA A260:A280 ratio of outside of 1.8-2.0 range; Frozen blood EDTA tube

Test Details


Use

To diagnose the mitochondrial DNA deletion syndromes. The test is also useful in assessing variants of uncertain significance in nuclear DNA genes and mtDNA genes that cause mtDNA deletion syndromes. Mitochondrial DNA (mtDNA) deletion syndromes predominantly comprise three overlapping phenotypes that are usually simplex (i.e., a single occurrence in a family), but rarely may be observed in different members of the same family or may evolve in a given individual over time. The three phenotypes are Kearns-Sayre syndrome (KSS), Pearson syndrome, and progressive external ophthalmoplegia (PEO). Rarely Leigh syndrome can be a manifestation of a mtDNA deletion. KSS is a multisystem disorder defined by the triad of onset before age 20 years, pigmentary retinopathy, and PEO. In addition, affected individuals have at least one of the following: cardiac conduction block, cerebrospinal fluid protein concentration greater than 100 mg/dL, or cerebellar ataxia. Onset is usually in childhood. Pearson syndrome is characterized by sideroblastic anemia and exocrine pancreas dysfunction and is usually fatal in infancy. PEO, characterized by ptosis, paralysis of the extraocular muscles (ophthalmoplegia), oropharyngeal weakness, and variably severe proximal limb weakness, is relatively benign. Mitochondrial DNA deletions generally occur de novo and thus cause disease in one family member only, with an approximate recurrence risk of 1 in 24. Multiple mtDNA deletions cause tissue-specific cytochrome c oxidase (COX) deficiency. Inheritance 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).

Methodology

Next-Generation Sequencing

Recommended MNG Kits

SINGLE Blood Genetic Testing