Optic Atrophy 7 (OPA7) via the TMEM126A Gene
Summary and Pricing 
Test Method
Exome Sequencing with CNV Detection
| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 9029 | TMEM126A | 81479 | 81479,81479 | $990 | Order Options and Pricing |
Pricing Comments
Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information. If the Sanger option is selected, CNV detection may be ordered through Test #600.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).
Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).
The Sanger Sequencing method for this test is NY State approved.
For Sanger Sequencing click here.Turnaround Time
3 weeks on average for standard orders or 2 weeks on average for STAT orders.
Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.
Targeted Testing
For ordering sequencing of targeted known variants, go to our Targeted Variants page.
Clinical Features and Genetics
Clinical Features
Optic Atrophy (OA) is the most prevalent inherited optic neuropathy besides Leber’s hereditary optic neuropathy (LHON). Both share a common pathological hallmark, the preferential loss of retinal ganglion cells (RGCs) (Carelli et al. 2009; Yu-Wai-Man et al. 2010). OA is clinically characterized by bilateral reduction in visual acuity that progresses insidiously from early childhood onwards (Yu-Wai-Man et al. 2011). Other symptoms include central or near central scotomas, tritanopia, variable degree of ptosis, central visual field defects and/or ophthalmalgia and optic nerve pallor. The most common OA is inherited in an autosomal dominant (AD) mode (DOA). Phenotype-genotype studies found that 20% of DOA patients develop a more severe phenotype called “DOA plus” (DOA+), which is characterized by extraocular multi-systemic features, including neurosensory hearing loss, or less commonly chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like illness, spastic paraplegia or cataracts (Yu-Wai-Man et al. 2010; Amati-Bonneau et al. 2009). Disease prevalence is estimated as ~1/30,000 in most populations in the world, but in Denmark it can reach to 1/10,000 due to a founder effect (Kjer et al. 1996; Thiselton et al. 2001; Lenaers et al. 2012). Autosomal recessive (AR) optic atrophies are not commonly reported.
Genetics
Hereditary optic atrophies exhibit AD, AR, X-linked recessive, or maternal (mitochondrial DNA defects) inheritance. Nonsyndromic autosomal recessive optic atrophy is caused by a mutation in the TMEM126A gene. Very mild but progressive sensorineural hearing loss has been reported in some TMEM126A-associated optic atrophy patients. The only causative mutation that has been reported in TMEM126A is the nonsense mutation p.Arg55* (c.163C>T), which is reported to be a founder mutation originating ~2,400 years ago (~80 generations) (Hanein et al. 2009). TMEM126A encodes an inner mitochondrial membrane associated cristae protein of higher eukaryotes, which is highly expressed in retinal cellular compartments that are highly enriched with mitochondria. The second transmembrane domain of this protein is required for its mitochondrial localization and the function of RGCs in higher eukaryotes. (Hanein et al. 2009; Meyer et al. 2010; Hanein et al. 2013). Mutations in TMEM126A would affect the mitochondrial localization and in turn the high-energy-demanding RGSs and lead to optic atrophy (Hanein et al. 2009).
Clinical Sensitivity - Sequencing with CNV PGxome
The only reported TMEM126A causative mutation (c.163C>T; p.Arg55*) was identified in North African families (Maghrebian, Algerian, Tunisian and Moroccan) (Desir et al. 2012; Hanein et al. 2009; Meyer et al. 2010).
Testing Strategy
This test provides full coverage of all coding exons of the TMEM126A gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).
Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).
Indications for Test
Patients with isolated nonsyndromic optic atrophy, especially in juvenile forms are candidates. All patients from the Maghreb region (North Africa) are suggested to consider targeted testing for the c.163C>T (p.Arg55*) (Hanein et al. 2009; Meyer et al. 2010). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in TMEM126A.
Patients with isolated nonsyndromic optic atrophy, especially in juvenile forms are candidates. All patients from the Maghreb region (North Africa) are suggested to consider targeted testing for the c.163C>T (p.Arg55*) (Hanein et al. 2009; Meyer et al. 2010). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in TMEM126A.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| TMEM126A | 612988 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Optic Atrophy 7 | AR | 612989 |
Related Test
| Name |
|---|
| Optic Atrophy and Neuropathy Panel |
Citations
- Amati-Bonneau P, Milea D, Bonneau D, Chevrollier A, Ferré M, Guillet V, Gueguen N, Loiseau D, Crescenzo M-AP de, Verny C, Procaccio V, Lenaers G, et al. 2009. OPA1-associated disorders: phenotypes and pathophysiology. Int. J. Biochem. Cell Biol. 41: 1855–1865. PubMed ID: 19389487
- Carelli V, Morgia C La, Valentino ML, Barboni P, Ross-Cisneros FN, Sadun AA. 2009. Retinal ganglion cell neurodegeneration in mitochondrial inherited disorders. Biochimica et Biophysica Acta (BBA) - Bioenergetics 1787: 518–528. PubMed ID: 19268652
- Desir J, Coppieters F, Regemorter N Van, Baere E De, Abramowicz M, Cordonnier M. 2012. TMEM126A mutation in a Moroccan family with autosomal recessive optic atrophy. Mol Vis 18: 1849–1857. PubMed ID: 22815638
- Hanein S, Garcia M, Fares-Taie L, Serre V, Keyzer Y De, Delaveau T, Perrault I, Delphin N, Gerber S, Schmitt A, Masse J-M, Munnich A, et al. 2013. TMEM126A is a mitochondrial located mRNA (MLR) protein of the mitochondrial inner membrane. Biochim. Biophys. Acta 1830: 3719–3733. PubMed ID: 23500070
- Hanein S, Perrault I, Roche O, Gerber S, Khadom N, Rio M, Boddaert N, Jean-Pierre M, Brahimi N, Serre V, Chretien D, Delphin N, et al. 2009. TMEM126A, Encoding a Mitochondrial Protein, Is Mutated in Autosomal-Recessive Nonsyndromic Optic Atrophy. The American Journal of Human Genetics 84: 493–498. PubMed ID: 19327736
- Kjer B, Eiberg H, Kjer P, Rosenberg T. 1996. Dominant optic atrophy mapped to chromosome 3q region. II. Clinical and epidemiological aspects. Acta Ophthalmol Scand 74: 3–7. PubMed ID: 8689476
- Lenaers G, Hamel C, Delettre C, Amati-Bonneau P, Procaccio V, Bonneau D, Reynier P, Milea D. 2012. Dominant optic atrophy. Orphanet J Rare Dis 7: 46–46. PubMed ID: 22776096
- Meyer E, Michaelides M, Tee LJ, Robson AG, Rahman F, Pasha S, Luxon LM, Moore AT, Maher ER. 2010. Nonsense mutation in TMEM126A causing autosomal recessive optic atrophy and auditory neuropathy. Molecular vision 16: 650. PubMed ID: 20405026
- Thiselton DL, Alexander C, Morris A, Brooks S, Rosenberg T, Eiberg H, Kjer B, Kjer P, Bhattacharya SS, Votruba M. 2001. A frameshift mutation in exon 28 of the OPA1 gene explains the high prevalence of dominant optic atrophy in the Danish population: evidence for a founder effect. Human genetics 109: 498–502. PubMed ID: 11735024
- Yu-Wai-Man P, Griffiths PG, Burke A, Sellar PW, Clarke MP, Gnanaraj L, Ah-Kine D, Hudson G, Czermin B, Taylor RW, Horvath R, Chinnery PF. 2010. The Prevalence and Natural History of Dominant Optic Atrophy Due to OPA1 Mutations. Ophthalmology 117: 1538–1546.e1. PubMed ID: 20417570
- Yu-Wai-Man P, Shankar SP, Biousse V, Miller NR, Bean LJH, Coffee B, Hegde M, Newman NJ. 2011. Genetic Screening for OPA1 and OPA3 Mutations in Patients with Suspected Inherited Optic Neuropathies. Ophthalmology 118: 558–563. PubMed ID: 21036400
Ordering/Specimens
Ordering Options
We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.
myPrevent - Online Ordering
- The test can be added to your online orders in the Summary and Pricing section.
- Once the test has been added log in to myPrevent to fill out an online requisition form.
- PGnome sequencing panels can be ordered via the myPrevent portal only at this time.
Requisition Form
- A completed requisition form must accompany all specimens.
- Billing information along with specimen and shipping instructions are within the requisition form.
- All testing must be ordered by a qualified healthcare provider.
For Requisition Forms, visit our Forms page
If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.
Specimen Types
Specimen Requirements and Shipping Details
PGxome (Exome) Sequencing Panel
PGnome (Genome) Sequencing Panel
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