ARUP's Laboratory Test Directory

von Willebrand Disease, Type 2A (VWF) Sequencing Exon 28 with Reflex to 9 Exons : 2005480
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Patient History for von Willebrand (VWD) Testing
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Additional Technical Information


Mnemonic: VWF2A SEQ

Ordering Recommendation: Molecular testing to confirm a phenotypic diagnosis of von Willebrand disease type 2A.
Methodology: Polymerase Chain Reaction/Sequencing
Performed: Varies
Reported: Within 28 days
Specimen Required: Collect: Lavender (EDTA), pink (K2EDTA) or yellow (ACD Solution A or B).

Specimen Preparation: Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature: Refrigerated.

Stability (collection to initiation of testing): Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Reference Interval:
By report
Interpretive Data: Background Information for von Willebrand Disease, Type 2A (VWF) Sequencing Exon 28 with Reflex to 9 Exons.
Characteristics: Mucocutaneous bleeding after brushing or flossing teeth, unexplained bruising, prolonged repeated nosebleeds, menorrhagia, and prolonged bleeding following childbirth, trauma or surgery.
Incidence: Approximately 1 in 100 to 1 in 1000 individuals.
Inheritance: Autosomal dominant for types 2B, 2M and most of 2A; autosomal recessive for 20 percent of 2A.
Penetrance: Dominant mutations are incompletely penetrant when VWF: Ag and VWF: RCo levels are 25-50 IU/dL. Full penetrance is expected when VWF: Ag and VWF: RCo levels are less than 25 IU/dL.
Cause: Pathogenic VWF mutations.
Clinical Sensitivity: 99 percent for vWD type 2A and 80 percent for types 2B and 2M; unknown for other vWD subtypes.
Methodology: Bidirectional sequencing of VWF exon 28 and its intron-exon boundaries; if no pathogenic mutations are detected, bidirectional sequencing of exons 11, 12, 14, 15, 16, 24, 25, 51, and 52 and the corresponding intron-exon boundaries is performed.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Rare diagnostic errors can occur due to primer site mutations. Regulatory region mutations, deep intronic mutations, and large deletion/duplications will not be detected. Mutations lying outside of VWF exons 11, 12, 14, 15, 16, 24, 25, 28, 51 and 52 are not evaluated.




Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
Note: Exon 28 sequencing is performed on all samples. If results do not explain the clinical scenario, then sequencing of 9 exons (11, 12, 14, 15, 16, 24, 25, 51 and 52) will be added. Additional charges apply.
CPT Code(s): 81403; If reflexed, add 81406
Cross References: VWF2A Sequencing