| Test code: | 479 |
| Type of disorder: | Mitochondrial Disorders |
| Disease(s) tested for: | Mitochondrial Disease associated with Mitochondrial Depletion Syndrome |
| Profiles that contain this test: | Mitochondrial Hepatoencephalopathic Evaluation Progressive External Ophthalmoplegia Evaluation |
| Informed Consent Required: | This test requires physician attestation that patient consent has been received |
| Clinical Significance: | Identifies mutations in the TWINKLE (PEO1/C10orf2) gene related to mitochondrial DNA depletion Typical Presentation: Mitochondrial disease is a clinically heterogeneous group of multisystem disorders characterized by muscle weakness and wasting caused by mutations of nuclear or mitochondrial DNA. PEO phenotype, including features such as ptosis, ophthalmoplegia, hearing loss, sensory axonal neuropathy, and severe hepatocerebral phenotype characterized by neonatal hypotonia, mild liver insufficiency, increased serum and CSF lactate, psychomotor retardation, seizures, and peripheral neuropathyproximal muscle weakness. Twinkle (PEO1/C10orf2) is also associated with abnormal gait, dysphagia, dysphonia, and late-onset dementia the seventh or eighth decade. Other symptoms have been cited in the literature such as myopathy, usually described as limb-girdle, polyneuropathy, brainstem symptoms, depression, and parkinsonism or tremors , with less frequent features including diabetes mellitus, ataxia, cataract, memory loss, hearing loss, and cardiac problems. Indications for testing: Symptomatic individuals consistent with hepatoencephalopathic forms of mitochondrial disease. |
| Methodology: | Sanger Sequencing |
| Reference Range: | No mutations detected |
The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.
| CPT: | 81404(1) |
Please label each specimen tube with two forms of patient identification. These forms of identification must also appear on the requisition form.
| Specimen Type: | Whole blood |
| Specimen Stability: | Room temperature: 10 days, Refrigerated: 10 days, Frozen: Unacceptable, |
| Specimen Requirements: | 8 mL (6 mL minimum) whole blood collected in two (lavender-top) EDTA tubes. Pediatric (0-3 years): 2 mL (1 mL minimum) |
| Instructions: | Higher blood volumes ensure adequate DNA quantity, which varies with WBC, specimen condition, and need for confirmatory testing. Patients, 0-3 years have higher WBC, yielding more DNA per mL of blood |
| Transport Temperature: | Room temperature |
| Set-up/Analytic Time: | 14-28 days |
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