Mitochondrial DNA Deletion Analysis

Whole blood, oral swab, or extracted DNA

4 mL, 1 swab, or 200 ng of DNA

1 mL, 1 swab, or 100 ng of DNA

Whole blood: lavender-top (EDTA) tube; oral swab: OCD-100 DNA Genotek device only; extracted DNA: sterile screw capped vial

• Room temperature: 5 days

• Refrigerated: 5 days

•Frozen: Do not freeze

This test is used 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).

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

Next-Generation Sequencing