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Leber Hereditary Optic Neuropathy (LHON)

LHON

Test Codes

BAYLOR: 2010, Testing requires pathology approval prior to collection.

Department

Send Outs

Instructions

This test is not included in the Beaumont Laboratory testing formulary, however, the Laboratory can facilitate specimen collection.

• This test requires pathology review. Contact the Send Outs Laboratory at 248-551-9045 before ordering this test.
• Testing requires the ordering physician to complete forms for the independent clinical laboratory performing the testing.
• This test will be billed to the patient's insurance. If not covered by insurance, the patient is responsible for the full cost of testing.
• Specimens received without the appropriate forms and information will not be shipped.
• Once approved, order test as a Miscellaneous Send Outs (XMISC). 

Specimen Collection Criteria

Collect (Adults): Two Lavender-top EDTA tubes, after obtaining necessary pathology approval.
Also acceptable (Children/Infants): One Lavender-top EDTA tube, after obtaining necessary pathology approval.

Physician Office/Draw Specimen Preparation

Do not centrifuge. Maintain whole blood specimens at room temperature (20-26°C or 68-78.8°F).

Preparation for Courier Transport

Transport: Whole blood in EDTA tubes, at room temperature (20-26°C or 68-78.8°F)(Minimum: 3.0 mL Adult) (Minimum: 2.0 mL Children).

Rejection Criteria

• Specimens received without prior laboratory notification and review.
• Specimens not collected and processed as indicated. 

In-Lab Processing

Do not centrifuge. Maintain whole blood specimens at room temperature (20-26°C or 68-78.8°F).

Transport: Whole blood in EDTA tubes, at room temperature (20-26°C or 68-78.8°F)(Minimum: 3.0 mL Adult) (Minimum: 2.0 mL Children).

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 days
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Baylor Genetics, DNA Diagnostic Laboratory, Houston, TX.

Performed

Results available within 3-4 weeks.

Reference Range

By report.

Test Methodology

Next Generation Sequencing.

Interpretation

By report.

Clinical Utility

Specific mutations at mtDNA nucleotide positions 11778 (ND4 gene), 3460 (ND1 gene), and 14484 (ND6 gene) are considered primary causes of Leber Hereditary Optic Neuropathy in greater than 95% of patients of northern European descent worldwide. In addition, the 15257 mutation (CYB) is also considered by some investigators to be a primary LHON mutation. The primary LHON mutations show markedly reduced penetrance. The presence of any one of these mutations in a symptomatic individual can be considered diagnostic for LHON, however, asymptomatic individuals who carry a primary LHON mutation do not necessarily develop symptoms or progress to blindness. Only about 50% of index cases have a family history. Mitochondrial genetics are characterized by maternal transmission and by mtDNA heteroplasmy (variation in the relative proportions of normal and mutant mtDNA) in tissues. The detection of mutant mitochondrial DNA in peripheral blood does NOT provide a measure of heteroplasmy in other tissues. Hence, it is difficult to provide definitive counseling information to unaffected family members who may harbor a LHON primary mutation.

Reference

1. Wong LJC, Boles R. (2005) Mitochondrial DNA in clinical laboratory diagnostics. Review Article, Clinica Chimica Acta 354: 1-20.
2. Shanske S, Wong LJC. (2004) Molecular analysis for mitochondrial DNA disorders. Mitochondrion 4: 403-415.
3. Liang MH, Wong LJC. (1998) Yield of mtDNA mutation analysis in 2000 patients. Am. J. Med. Genet. 77: 395-400.
4. Wong LJC, Senadheera D. (1997) Direct detection of multiple point mutations in mitochondrial DNA Clinical Chemistry 43: 1857-1861.

CPT Codes

81465

Contacts

Last Updated

10/3/2023