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Joubert Syndrome via the AHI1 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
11017 AHI1 81407 81407,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11017AHI181407 81407(x1), 81479(x1) $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

  • Fang Xu, PhD, FACMG

Clinical Features and Genetics

Clinical Features

Joubert syndrome (JS) (OMIM 213300) 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. For more information, see Parisi and Glass (GeneReviews, 2007) and Parisi et al. (Eur J Hum Genet 15:511-521, 2007).

Genetics

JS is inherited in an autosomal recessive manner. Variants in the AHI1 gene cause JS (Ferland et al. Nat Genet 36:1008-1013, 2004; Dixon-Salazar et al. Am J Hum Genet 75:979-987, 2004; Parisi et al. J Med Genet 43:334-339, 2006; Valente et al. Ann Neurol 59:527-534, 2006). The AHI1 gene encodes the AHI1 protein, or jouberin, which has been predicted to have a role in cilia-associated trafficking mechanisms (Louie et al. Nat Genet 42:175-180, 2010). It has also been reported that the AHI1 protein is required for photoreceptor outer segment development. It modifies the retinal degeneration phenotype in nephronophthisis through direct interaction with nephrocystin-1 (NPHP1) (Louie et al. 2010; Eley et al. Kidney Int 74:1139- 1149, 2008). A mix of nonsense, frameshift, splicing, deletion, insertion, and missense variants has been reported in the AHI1 gene; none are particularly frequent (Ferland et al. 2004; Dixon-Salazar et al. 2004; Parisi et al. 2006; Valente et al. 2006). Other cases of JS have also been linked to variants in the TMEM67/MKS3, CEP290, CC2D2A, RPGRIP1L, INPP5E, ARL13, TMEM216, and NPHP1 genes. PreventionGenetics performs tests for all of these genes.

Clinical Sensitivity - Sequencing with CNV PGxome

The prevalence of JS is about 1 in 100,000. The following are the approximate fractions of patients with variants in the indicated genes for Joubert syndrome: AHI1 10%, TMEM67/MKS3 10%, CC2D2A 10%, CEP290 10%, RPGRIP1L 2%, ARL13B 2%, NPHP1 2% (Parisi et al. Eur J Hum Genet 15:511-521, 2007).

Testing Strategy

This test provides full coverage of all coding exons of the AHI1 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 JS and family members of patients who have known variants. Conclusive connections between clinical features and individual mutated genes have not yet been made. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in AHI1.

Gene

Official Gene Symbol OMIM ID
AHI1 608894
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Joubert Syndrome 3 AR 608629

Citations

  • Berdon, W. E., et.al. (2011). "Clinical and radiological distinction between spondylothoracic dysostosis (Lavy-Moseley syndrome) and spondylocostal dysostosis (Jarcho-Levin syndrome)." Pediatr Radiol 41(3): 384-8. PubMed ID: 21174082
  • Dixon-Salazar, T., et.al. (2004). "Mutations in the AHI1 gene, encoding jouberin, cause Joubert syndrome with cortical polymicrogyria." Am J Hum Genet 75(6): 979-87. PubMed ID: 15467982
  • Ferland, R. J., et.al. (2004). "Abnormal cerebellar development and axonal decussation due to mutations in AHI1 in Joubert syndrome." Nat Genet 36(9): 1008-13. PubMed ID: 15322546
  • Louie, C. M., et.al. (2010). "AHI1 is required for photoreceptor outer segment development and is a modifier for retinal degeneration in nephronophthisis." Nat Genet 42(2): 175-80. PubMed ID: 20081859
  • Parisi M, Glass I. 2013. Joubert Syndrome and Related Disorders. In: Pagon RA, Adam MP, Ardinger HH, Bird TD, Dolan CR, Fong C-T, Smith RJ, and Stephens K, editors. GeneReviews(®), Seattle (WA): University of Washington, Seattle. PubMed ID: 20301500
  • Parisi MA, Doherty D, Chance PF, Glass IA. 2007. Joubert syndrome (and related disorders) (OMIM 213300). Eur. J. Hum. Genet. 15: 511–521. PubMed ID: 17377524
  • Parisi, M. A., et.al. (2006). "AHI1 mutations cause both retinal dystrophy and renal cystic disease in Joubert syndrome." J Med Genet 43(4): 334-9. PubMed ID: 16155189
  • Valente, E. M., et.al. (2006). "AHI1 gene mutations cause specific forms of Joubert syndrome-related disorders." Ann Neurol 59(3): 527-34. PubMed ID: 16453322

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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