Diabetes Insipidus: Arginine Vasopressin V2 Receptor (AVPR2) Sequencing

Diagnostic Use

X-linked nephrogenic diabetes insipidus (NDI) is a rare disease with defective renal and extrarenal Arginine-Vasopressin V2 receptor responses due to inactivating mutations in the AVPR2 gene. Affected male patients are unable to concentrate their urine after the administration of the antidiuretic hormone arginine-vasopressin (AVP). They consequently present with polyuria, polydipsia and, if unable to maintain fluid intake, hypernatermia. Individuals have also been described who present with a nephorgenic syndrome of inappropriate antidiuresis. These individuals present with persistent hyponatremia with an inability to excrete a maximally dilute urine and exhibit unmeasurable AVP level. These patients have gain-of-function mutations in the AVPR2 gene which cause constitutive activation of the receptor with water retention and consequent hyponatremia.

Department

Genetics - Molecular Pathology

Delphic Registration Code

MOLP

Constituent Tests

• Genomic DNA Extraction

Synonyms

NDI

Turnaround Time

4 weeks

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

4.0

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

1.0

Minimum Sample Volume (ml)

0.5

Additional Specimen Information

This test requires nucleated cells. Please do not centrifuge or freeze blood samples.
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Aliquot Instructions

Sample Type

• Whole Blood

Transport to Lab

Ambient (8 - 24 degrees Celsius)

Additional Referral/Aliquot Information

This test requires nucleated cells. Please do not centrifuge or freeze blood samples.
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Test Method

All three coding exons of the AVPR2 gene are amplified using the polymerase chain reaction (PCR) and analysed by automated bidirectional fluorescent DNA sequencing.

Non-Funded Test Cost

$949.14 (Exclusive of GST)

Billing Code

4566

Uncertainty of Measurement:
Automated bidirectional DNA sequencing has an analytical sensitivity and specificity of >99%. Note that the lower limit of variant detection of sequencing analysis is ~10%, this is important to consider in the case of mosaicism, mitochondrial, and somatic variation that is not expected to be present at 50% or 100%. This analysis will not detect variants located within intronic regions, except at the intron-exon boundaries.

Genomic DNA must be extracted from the specimen prior to testing. This incurs an additional charge (see GDNA). Laboratories may prefer to submit DNA for testing. Please provide a minimum of 5 micrograms of DNA at 20 nanograms/microlitre.

Contact Information

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