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Spinocerebellar Ataxia 21 via the TMEM240 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
TMEM240 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8597TMEM24081479 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.

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.


Genetic Counselors


  • Angela Gruber, PhD

Clinical Features and Genetics

Clinical Features

The spinocerebellar ataxias (SCAs) are a genetically and clinically heterogeneous group of inherited neurological disorders characterized by degeneration of neurons in the cerebellum and associated pathways. The SCAs are classified according to the genetic loci: SCA1 through SCA40 (Tsoi et al. 2014). Slowly progressive cerebellar dysfunction is a feature of each type of SCA syndrome in association with various oculomotor, pyramidal/extrapyramidal, sensory, and cognitive/behavioral symptoms that vary with the underlying affected gene. There is great variability in the age of onset, associated symptoms and disease progression (Bushart et al. 2016; Meera et al. 2016).

Spinocerebellar Ataxia 21 (SCA21) was reported in a four generation French family with characteristics including early onset, mild to severe cognitive impairment, motor clumsiness, and slow progression (Vuillaume et al. 2002). Analysis of 368 additional French families with autosomal dominant cerebellar ataxia identified 6 different heterozygous pathogenic variants in the TMEM240 gene (Delplanque et al. 2014).


Spinocerebellar ataxia 21 (SCA21) is an autosomal dominant neurologic disorder caused by pathogenic variants in TMEM240 (Delplanque et al. 2014). TMEM240 encodes a transmembrane-domain containing protein expressed in the brain and cerebellum. TMEM240 contains four exons, encodes 173 amino acids and is located at 1p36.33. The mechanism by which pathogenic variants in TMEM240 cause SCA21 disease remains unclear. It is possible that variants in the membrane-spanning protein TMEM240 interfere with the function of other channel proteins in the neuronal cell membrane (Zeng et al. 2016). Most reported pathogenic variants in TMEM240 are missense or nonsense. No large deletions or duplications have been reported.

Clinical Sensitivity - Sequencing with CNV PGxome

Precise estimates of clinical sensitivity are not available because only a limited number of patients have been reported. However, pathogenic TMEM240 variants are not a common cause of Spinocerebellar Ataxia.

Testing Strategy

This test provides full coverage of all coding exons of the TMEM240 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

All patients with symptoms suggestive of Spinocerebellar ataxia 21 are candidates for this test.


Official Gene Symbol OMIM ID
TMEM240 616101
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Spinocerebellar Ataxia 21 AD 607454


  • Bushart D.D et al. 2016. Annals of Translational Medicine. 4: 25. PubMed ID: 26889478
  • Delplanque J. et al. 2014. Brain. 137: 2657-63. PubMed ID: 25070513
  • Meera P. et al. 2016. The Journal of physiology. PubMed ID: 27198167
  • Tsoi H. et al. 2014. Journal of Medical Genetics. 51: 590-5. PubMed ID: 25062847
  • Vuillaume I. et al. 2002. Annals of Neurology. 52: 666-70. PubMed ID: 12402269
  • Zeng S. et al. 2016. Scientific Reports. 6: 19897. PubMed ID: 26813285


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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View Ordering Instructions

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2) Select Additional Test Options

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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