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Liddle Syndrome and Autosomal Recessive Pseudohypoaldosteronism Type 1 via the SCNN1G 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
11651 SCNN1G 81406 81406,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11651SCNN1G81406 81406,81479 $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. 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 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

  • Angela Gruber, PhD

Clinical Features and Genetics

Clinical Features

Liddle syndrome (OMIM #177200) is an inherited disorder of sodium reabsorption in the renal distal tubules characterized by severe early onset of hypertension with hypokalemia, metabolic alkalosis, low plasma renin activity, and suppressed aldosterone secretion (Botero-Velez et al. N Engl J Med 330(3):178-181, 1994; Shimkets et al. Cell 79(3):407-414, 1994). Untreated hypertension in these patients can progress with age to renal failure, heart disease or stroke.

Autosomal recessive pseudohypoaldosteronism type 1 (PHA1; OMIM #264350) is a multi-organ life-threatening disorder characterized by severe neonatal onset salt wasting and high concentrations of sodium in sweat, stool, and saliva (Chang et al. Nat Genet 12(3):248-253, 1996; Scheinman et al. N Engl J Med 340(15):1177-1187, 1999). Clinical features include hyponatremia, hyperkalaemia, metabolic acidosis, unresponsiveness to mineralocorticoid hormones, and increased plasma renin activity with high serum aldosterone concentrations. Compared with autosomal dominant PHA1, the recessive form of the disease is a more severe systemic condition with persistence into adulthood. Some patients had recurrent respiratory problems (Chang et al., 1996; Schaedel et al. J Pediatr 135(6):739-745, 1999). Genetic confirmation is essential for distinguishing autosomal recessive PHA1 from cystic fibrosis-like disease (Sheridan et al. Hum Mol Genet 14(22):3493-3498, 2005; Azad et al. Hum Mutat 30(7):1093-1103, 2009; Mora-Lopez et al. Eur J Pediatr 171(6):997-1000, 2012).

Genetics

Autosomal recessive PHA1 can be caused by mutations in any one of the three genes (SCNN1A, SCNN1B and SCNN1G) encoding the epithelial sodium channel (ENaC) while Liddle syndrome is an autosomal dominant disorder caused by mutations in SCNN1B or SCNN1G (Shimkets et al., 1994; Hansson et al. Nat Genet 11(1):76-82, 1995; Chang et al., 1996). These amiloride-sensitive channels play a key role in electrolyte transportation across epithelia in many organs. SCNN1G has 12 coding exons that encode the gamma subunit of ENaC. Genetic defects located throughout the SCNN1G gene include missense, nonsense, splicing mutations and small deletion/insertions. Gross deletions and duplications within the SCNN1G gene have not been reported (Human Gene Mutation Database).

Clinical Sensitivity - Sequencing with CNV PGxome

SCNN1G mutation detection rate in a large cohort of patients is unavailable because these mutations have been only reported in individual cases. Mutations in SCNN1G are less common than mutations in SCNN1A and SCNN1B (Human Gene Mutation Database).

Testing Strategy

This test provides full coverage of all coding exons of the SCNN1G 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 Liddle syndrome or autosomal recessive PHA1. Testing is also indicated for family members of patients who have known SCNN1G mutations. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SCNN1G.

Gene

Official Gene Symbol OMIM ID
SCNN1G 600761
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Citations

  • Azad, A. et al. (2009). PubMed ID: 19462466
  • Botero-Velez, M. et al. (1994). “Liddle's syndrome revisited - a disorder of sodium reabsorption in the distal tubule.” N Engl J Med 330(3):178-181. PubMed ID: 8264740
  • Chang, S. et al. (1996). PubMed ID: 8589714
  • Hansson, J. et al. (1995). PubMed ID: 7550319
  • Human Gene Mutation Database (Bio-base).
  • Mora-Lopez, F. et al. (2012). “Novel mutation in the epithelial sodium channel causing type I pseudohypoaldosteronism in a patient misdiagnosed with cystic fibrosis.” Eur J Pediatr 171(6):997-1000. PubMed ID: 22371258
  • Schaedel, C. et al. (1999). PubMed ID: 10586178
  • Scheinman, S. et al. (1999). “Genetic disorders of renal electrolyte transport.” N Engl J Med 340(15):1177-1187. PubMed ID: 10202170
  • Sheridan, M. et al. (2005). “Mutations in the beta-subunit of the epithelial Na+ channel in patients with a cystic fibrosis-like syndrome.” Hum Mol Genet  14(22):3493-3498. PubMed ID: 16207733
  • Shimkets, R. et al. (1994). PubMed ID: 7954808

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.
Total Price: $
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