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Joubert Syndrome via the INPP5E Gene

Summary and Pricing

Test Method

Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
INPP5E 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
15165INPP5E81479 81479,81479 $990 Order Options and Pricing

Pricing Comments

Testing run on PG-select capture probes includes CNV analysis for the gene(s) on the panel but does not permit the optional add on of exome-wide CNV analysis. Any of the NGS platforms allow reflex to other clinically relevant genes, up to whole exome or whole genome sequencing depending upon the base platform selected for the initial test.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

This test is also offered via a custom panel (click here) on our exome or genome backbone which permits the optional add on of exome-wide CNV or genome-wide SV analysis.

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

Ciliopathies are a group of related disorders that include Joubert syndrome (OMIM 213300), Meckel-Gruber syndrome (OMIM 249000), nephronophthisis (OMIM 256100) and Bardet-Biedl syndrome (OMIM 209900). All of the ciliopathies are caused by variants in genes encoding proteins involved in cilia/centrosome structure and function (Hildebrandt and Otto Nat Rev Genet 6:928-940, 2005; http://v3.ciliaproteome.org/cgi-bin/index.php). Clinical features of the ciliopathies overlap. Joubert syndrome (JS) is marked by hypotonia, abnormal ocular movements, neonatal respiratory difficulties, mental retardation, hypoplasia of the cerebellar vermis, and malformation of the brainstem. The brain malformations lead to the "molar tooth sign" on cranial MRI, which is the hallmark clinical feature of JS. Other variable JS features include cystic kidneys, nephronophthisis, retinal dystrophy, ocular coloboma, occipital encephalocele, polydactyly, ataxia, and hepatic fibrosis.


Joubert syndrome exhibits autosomal recessive inheritance. All of the ciliopathies have high levels of locus heterogeneity. The INPP5E gene has recently been reported to be mutated in Joubert syndrome (the JBTS1 locus) (Bielas et al. Nat Genet 41:1032-1036, 2009) and MORM syndrome (mental retardation, obesity, retinal dystrophy and micropenis) (Jacoby et al. Nat Genet 41:1027-1031, 2009). INPP5E encodes the enzyme inositol polyphosphate-5-phosphatase E. MORM Syndrome is related in clinical features to Bardet-Biedl syndrome. The Joubert families all had missense variants, and the MORM family had a nonsense variant near the 3’ end of the gene.

Clinical Sensitivity - Sequencing with CNV PG-Select

The fraction of Joubert patients with variants in INPP5E is currently unknown (see also the CC2D2A Test Description).

Testing Strategy

This test is performed using Next-Generation sequencing with additional Sanger sequencing as necessary.

This test provides full coverage of all coding exons of the INPP5E gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

Patients with symptoms consistent with Joubert syndrome or MORM and who do not have variants in the most commonly mutated Joubert genes are candidates. Conclusive connections between clinical features and mutated genes have not yet been made. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in INPP5E.


Official Gene Symbol OMIM ID
INPP5E 613037
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Joubert Syndrome 1 AR 213300


  • Bielas, S. L., et.al. (2009). "Mutations in INPP5E, encoding inositol polyphosphate-5-phosphatase E, link phosphatidyl inositol signaling to the ciliopathies." Nat Genet 41(9): 1032-6. PubMed ID: 19668216
  • Hildebrandt, F., Otto, E. (2005). "Cilia and centrosomes: a unifying pathogenic concept for cystic kidney disease?." Nat Rev Genet 6(12): 928-40. PubMed ID: 16341073
  • Jacoby, M., et.al. (2009). "INPP5E mutations cause primary cilium signaling defects, ciliary instability and ciliopathies in human and mouse." Nat Genet 41(9): 1027-31. PubMed ID: 19668215


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

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View Ordering Instructions

1) Select Test Method (Platform)

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2) Select Additional Test Options

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