Diabetes Insipidus: AQP2 Sequencing

Diagnostic Use

Defects in AQP2 are the cause of Autosomal Nephrogenic Diabetes Insipidus (ANDI) [MIM:125800] also known as Diabetes Insipidus Nephrogenic Type 2. ANDI is caused by the inability of the renal collecting ducts to absorb water in response to AVP. It is characterised by excessive water drinking (polydipsia), excessive urine excretion (polyuria), persistent hypotonic urine, and hypokalemia. Inheritance can be autosomal dominant or recessive.

Department

Genetics - Molecular Pathology

Delphic Registration Code

MOLP

Constituent Tests

• Genomic DNA Extraction

Synonyms

ANDI
Diabetes Insipidus Nephrogenic

Turnaround Time

4 weeks

Test Code

4566

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 genetic test needs nucleated cells. Please don’t centrifuge or freeze the EDTA blood tube.
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 genetic test needs nucleated cells. Please don’t centrifuge or freeze the EDTA blood tube.
If storing blood tube prior to delivery please refrigerate at 4 degrees (transport still at ambient temperature).

Interpretation

Over 25 missense, nonsense and splicing mutations have been described in the coding exons. In addition, a number of small deletions and insertions have been described. Gross insertions and deletions have not been identified for this gene.

Test Method

All four coding exons of the AQP2 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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