Bartter Syndrome Type 2 via the KCNJ1 Gene
Summary and Pricing 
Test Method
Exome Sequencing with CNV Detection
| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 8723 | KCNJ1 | 81404 | 81404,81479 | $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.
Clinical Features and Genetics
Clinical Features
Bartter syndrome is a group of genetically heterogeneous renal tubular disorders characterized by renal hypokalaemia, metabolic alkalosis and secondary hyperaldosteronism with normal to low blood pressure due to a renal loss of sodium (Simon et al. 1996; Scheinman et al. 1999; Brochard et al. 2009). Bartter syndrome type 2 is an antenatal condition caused by loss-of-function mutations in the potassium channel Kir 1.1 (or ROMK) encoded by the KCNJ1 gene. Common clinical features include hypercalciuria with nephrocalcinosis, maternal polyhydramnios leading to premature birth, intrauterine and postnatal polyuria, recurrent vomiting, failure to thrive and growth retardation. The presence of early transitory hyperkalaemia suggests defects in KCNJ1.
Genetics
Bartter syndrome type 2 is an autosomal recessive disorder caused by defects in the KCNJ1 gene (Simon et al. 1996). KCNJ1 has two coding exons that encode the potassium channel Kir 1.1 (or ROMK), which plays an important role in potassium homeostasis. Genetic defects of KCNJ1 occur throughout the whole coding region and include missense, nonsense mutations and small deletion/insertions (Human Gene Mutation Database). Exon-level large deletions involving KCNJ1 have been also reported, but are uncommon.
Clinical Sensitivity - Sequencing with CNV PGxome
Detection rates of pathogenic variants in the KCNJ1 gene in a large cohort of patients with Bartter syndrome type 2 are unknown in the literature because documented KCNJ1 pathogenic variants have only been reported in limited cases.
Testing Strategy
This test provides full coverage of all coding exons of the KCNJ1 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 Bartter syndrome type 2. Testing is also indicated for family members of patients who have known KCNJ1 mutations. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in KCNJ1.
Candidates for this test are patients with Bartter syndrome type 2. Testing is also indicated for family members of patients who have known KCNJ1 mutations. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in KCNJ1.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| KCNJ1 | 600359 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Bartter Syndrome Antenatal Type 2 | AR | 241200 |
Related Test
| Name |
|---|
| Nephrolithiasis and Nephrocalcinosis Panel |
Citations
- Brochard K, Boyer O, Blanchard A, Loirat C, Niaudet P, Macher M-A, Deschenes G, Bensman A, Decramer S, Cochat P, Morin D, Broux F, et al. 2009. Phenotype-genotype correlation in antenatal and neonatal variants of Bartter syndrome. Nephrol. Dial. Transplant. 24: 1455–1464. PubMed ID: 19096086
- Human Gene Mutation Database (Bio-base).
- Scheinman SJ, Guay-Woodford LM, Thakker RV, Warnock DG. 1999. Genetic disorders of renal electrolyte transport. N. Engl. J. Med. 340: 1177–1187. PubMed ID: 10202170
- Simon DB, Karet FE, Rodriguez-Soriano J, Hamdan JH, DiPietro A, Trachtman H, Sanjad SA, Lifton RP. 1996. Genetic heterogeneity of Bartter’s syndrome revealed by mutations in the K+ channel, ROMK. Nat. Genet. 14: 152–156. PubMed ID: 8841184
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
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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ORDER OPTIONS
View Ordering Instructions1) Select Test Type
2) Select Additional Test Options
No Additional Test Options are available for this test.