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Mitochondrial Complex V Deficiency via the TMEM70 Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
8903 TMEM70 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8903TMEM7081479 81479,81479 $890 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.

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 backbone).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing backbone).

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

18 days on average for standard orders or 13 days 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.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Kym Bliven, PhD

Clinical Features and Genetics

Clinical Features

Primary mitochondrial complex V (CV) deficiency is considered the rarest oxidative phosphorylation (OXPHOS) complex disorder, accounting for approximately one percent of all OXPHOS disease (Rodenburg 2011). Although patients share a similar biochemical phenotype, displaying a significant decrease in the activity of mitochondrial complex V, the phenotypic disease spectrum can be broad (Hejzlarová et al. 2014; Jonckheere et al. 2012). Defects in CV-associated nuclear genes often result in a severe, neonatal-onset mitochondrial encephalopathy and/or cardiomyopathy. In contrast, pathogenic variants in genes encoded by the mitochondrial genome (such as MT-ATP6 or MT-ATP8) may lead to NARP (neuropathy, ataxia, and retinitis pigmentosa), MILS (maternally inherited Leigh syndrome), or bilateral striatal necrosis.

Patients with pathogenic variants in the TMEM70 gene usually present during the neonatal stage with CV deficiency, lactic acidosis, 3-methylglutaconic aciduria, and hypertrophic cardiomyopathy (Magner et al. 2015). Other symptoms may include hypotonia, respiratory distress, developmental delay, facial dysmorphism, pulmonary arterial hypertension, and/or microcephaly. TMEM70-associated CV deficiency may be more prevalent in patients with Roma ancestry due to the presence of a founder pathogenic variant in this population.

Genetics

Primary mitochondrial CV deficiency is caused by defects in the mitochondrial adenosine triphosphate (ATP) synthase, the fifth multi-subunit oxidative phosphorylation (OXPHOS) complex (Jonckheere et al. 2012; Hejzlarová et al. 2014). Although over 20 genes have been implicated in the assembly, structure, or function of the mitochondrial ATP synthase, variants in only six of these genes (ATP5A1, ATP5E, ATPAF2, TMEM70, MT-ATP6, and MT-ATP8) have been linked to disease to date. Depending on the cellular localization of the affected gene, this disorder may have an autosomal recessive or maternal mode of inheritance. Causative variants in the nuclear genes (ATP5A1, ATP5E, ATPAF2, and TMEM70) are inherited in an autosomal recessive (AR) manner. In contrast, causative variants in the MT-ATP6 or MT-ATP8 genes, which are encoded by the mitochondrial genome, are inherited in a maternal manner.

TMEM70 is required to maintain normal expression levels of complex V, although the exact function of this mitochondrial transmembrane protein is unknown (Cízková et al. 2008). Defects in the TMEM70 gene appear to be the most frequent cause of mitochondrial CV deficiency, with over fifteen unique variants reported in this gene to date (Hejzlarová et al. 2014; Magner et al. 2015). The majority of pathogenic changes in this gene are missense or nonsense variants, although several small deletions, insertions, and splicing variants have been described (Human Gene Mutation Database). Two large deletions in TMEM70 have also been reported (Jonckheere et al. 2011; Tort et al. 2011).

The pathogenic splicing variant, c.317-2A>G, is prevalent in the Roma population, although this variant has also been occasionally identified in patients of non-Roma origin (Magner et al. 2015).

Clinical Sensitivity - Sequencing with CNV PGxome

Defects in TMEM70 appear to be the most frequent cause of mitochondrial complex V deficiency, with over fifteen variants reported (Human Gene Mutation Database). No large cohort studies have been described to date, however, making clinical sensitivity difficult to estimate.

Testing Strategy

This test provides full coverage of all coding exons of the TMEM70 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

TMEM70 sequencing should be considered in patients with a family history of mitochondrial complex V deficiency, or patients who present with symptoms consistent with the disease. We will also sequence the TMEM70 gene to determine carrier status.

Gene

Official Gene Symbol OMIM ID
TMEM70 612418
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Related Test

Name
Mitochondrial Complex V Deficiency Panel (Nuclear Genes)

Citations

  • Cizkov√° A. et al. 2008. Nature Genetics. 40:1288-90. PubMed ID: 18953340
  • Hejzlarova K. et al. 2014. Physiological Research. 63:S57-1. PubMed ID: 24564666
  • Human Gene Mutation Database (Bio-base).
  • Jonckheere A.I. et al. 2011. Mitochondrion. 11:954-63. PubMed ID: 21945727
  • Jonckheere A.I. et al. 2012. Journal of Inherited Metabolic Disease. 35:211-25. PubMed ID: 21874297
  • Magner M. et al. 2015. J Inherit Metab Dis. 38:417-26. PubMed ID: 25326274
  • Rodenburg R.J. 2011. Journal of Inherited Metabolic Disease. 34:283-92. PubMed ID: 20440652
  • Tort F. et al. 2011. Clinical Genetics. 80:297-300. PubMed ID: 21815885

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


Specimen Types

Specimen Requirements and Shipping Details

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Method (Backbone)


1) Select Test Type


2) Select Additional Test Options

STAT and Prenatal Test Options are not available with Patient Plus.

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
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