Hearing Loss, Nonsyndromic, Mitochondrial DNA 2 Mutations (INACTIVE as of 05/20/2019: Refer to 2001992)
Ordering Recommendation

Diagnostic testing for individuals with nonsyndromic hearing loss (NSHL) and no identified variants in GJB2 or GJB6. Carrier screening if family history of m.1555A>G or m.7445A>G.

Polymerase Chain Reaction/Sequencing
7-14 days
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
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 
Reference Interval
By report
Interpretive Data
Background Information for Hearing Loss, Nonsyndromic, Mitochondrial DNA 2 Mutations
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.

Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Hotline History
Component Test Code*Component Chart NameLOINC
2002045HL mtDNA Specimen31208-2
2002046Hearing Loss, Nonsyndromic mtDNA Interp40995-3
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
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