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Meckel-Gruber Syndrome / Joubert Syndrome via the TCTN2 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
TCTN2 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11041TCTN281479 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.


Genetic Counselors


  • Fang Xu, PhD, FACMG

Clinical Features and Genetics

Clinical Features

Meckel-Gruber syndrome (MKS; OMIM 249000) is the most common form of syndromic neural tube defect. MKS is characterized by occipital encephalocele, polycystic kidneys, and postaxial polydactyly (Alexiev et al. Arch Pathol Lab Med 130:1236-1238, 2006). MKS is a common cause of prenatal echogenic kidneys (Chaumoitre et al. Ultrasound Obstet Gynecol 28:911-917, 2006). Nearly all MKS infants are stillborn or die shortly after birth. Joubert syndrome (JS; OMIM 213300) is marked by ataxia, hypotonia, abnormal eye movements, apraxia, neonatal respiratory anomalies, mental retardation, agenesis/hypoplasia of the cerebellar vermis, and a brain malformation known as the "molar tooth sign" (MTS) on cranial MRI. MTS is considered to be the most characteristic diagnostic feature. JS patients have substantial phenotypic variation. Some JS patients develop retinal dystrophy or progressive renal failure.


Both MKS and Joubert syndrome exhibit autosomal recessive inheritance. Both disorders have high levels of locus heterogeneity. Variants in the TCTN2 gene were reported to cause MKS8 and Joubert syndrome (Shaheen et al. Hum Mut 32:573, 2011; Sang et al. Cell 145:513, 2011). The TCTN2 gene encodes the tectonic 2 protein (TCTN2), which is predicted to interact with MKS1 protein and to regulate hedgehog-dependent neural tube patterning (Shaheen et al. 2011; Sang et al. 2011). Furthermore, Tctn2 null-mouse demonstrates that Tctn2 protein is required for ciliogenesis (Shaheen et al. 2011; Sang et al. 2011; Garcia-Gonzalo et al. Nat Genet 43:776, 2011). A mix of nonsense, splicing, and frameshift variants have been reported in the TCTN2 gene (Shaheen et al. 2011; Sang et al. 2011).

Clinical Sensitivity - Sequencing with CNV PGxome

The prevalence of the TCTN2 variants is currently unknown.

Testing Strategy

This test provides full coverage of all coding exons of the TCTN2 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

Candidates for this test are patients with symptoms consistent with MKS or Joubert syndrome and family members of patients. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in TCTN2.


Official Gene Symbol OMIM ID
TCTN2 613846
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Meckel Syndrome 8 AR 613885


  • Alexiev BA, Lin X, Sun CC, Brenner DS. 2006. Meckel-Gruber syndrome: pathologic manifestations, minimal diagnostic criteria, and differential diagnosis. Arch. Pathol. Lab. Med. 130: 1236-1238. PubMed ID: 16879033
  • Chaumoitre K, Brun M, Cassart M, Maugey-Laulom B, Eurin D, Didier F, Avni EF. 2006. Differential diagnosis of fetal hyperechogenic cystic kidneys unrelated to renal tract anomalies: A multicenter study. Ultrasound Obstet Gynecol 28: 911917. PubMed ID: 17094077
  • Garcia-Gonzalo, F. R., et.al. (2011). PubMed ID: 21725307
  • Sang, L., et.al. (2011). PubMed ID: 21565611
  • Shaheen, R., et.al. (2011). PubMed ID: 21462283


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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