For individuals with nonsyndromic hearing loss and no identified mutations in GJB2 or GJB6.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 2 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: mt-RNR1 m. 1555A>G is associated with non-syndromic hearing loss (NSHL) and a predisposition to aminoglycoside ototoxicity resulting in stable, severe to profound hearing loss with variable age of onset. mt-TS1 m.7445A>G is associated with progressive, mild to severe hearing loss of childhood onset and palmoplantar keratoderma.
Incidence: Approximately 1 in 50 individuals with NSHL has a mitochondrial mutation; 1 in 140,000 in the general population.
Inheritance: Dominant maternal inheritance.
Cause: Mitochondrial DNA mutations.
Mutations Tested: m.1555A>G and m.7445A>G.
Clinical Sensitivity: Dependent on ethnicity.
Methodology: Targeted bidirectional sequencing of mitochondrial mt-RNR1 m.1555A>G and mt-TS1 m.7445A>G.
Analytical Sensitivity and Specificity: 99 percent
Limitations:Diagnostic errors can occur due to rare sequence variations. Mutations other than the two targeted will not be identified. The etiology of hearing loss due to other genetic or environmental causes will not be determined.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2002045||HL mtDNA Specimen||31208-2|
|2002046||Hearing Loss, Nonsyndromic mtDNA Interp||40995-3|
- CX26 SEQ
- HL PANEL
- mtDNA sequending assay