Von Willebrand Disease Type 2N (Normandy): VWF Exons 18-24 Sequencing

Diagnostic Use

Von Willebrand disease (VWD) arises from a qualitative or quantitative deficiency of Von Willebrand factor (VWF), a multimeric protein that is required for platelet adhesion. A Type 2N (Normandy) defect causes a deficiency of the binding of VWF to factor VIII. This type gives a normal VWF antigen level and normal functional test results but has a low factor VIII. This has probably led to some 2N patients being misdiagnosed in the past as having hemophilia A, and should be suspected if the patient has the clinical findings of hemophilia A but a pedigree suggesting autosomal, rather than X-linked, inheritance.

Department

Genetics - Molecular Pathology

Delphic Registration Code

MOLP

Constituent Tests

• Genomic DNA Extraction

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

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

Exons 18-24 of the VWF gene are amplified using PCR and analysed using DNA sequencing.

Contact Canterbury Health Laboratories on +64 3 364 0484 or email LabInfo@cdhb.health.nz

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/microliter.

Contact Information

Enquiry Form