von Willebrand Disease, Type 2B (VWF) Sequencing
2005486
 
Ordering Recommendation
Molecular testing to confirm a phenotypic diagnosis of von Willebrand disease type 2B and to distinguish from pseudo (platelet-type) vWD.
Mnemonic
VWF2B SEQ
Methodology
Polymerase Chain Reaction/Sequencing
Performed
Varies
Reported
Within 21 days
New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory.
Specimen Required
Patient Preparation
 
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.  
Unacceptable Conditions
 
Remarks
 
Stability
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable  
Reference Interval
By report
Interpretive Data
Background Information for von Willebrand Disease, Type 2B (VWF) Sequencing:
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 in exon 28.
Clinical Sensitivity
: 80 percent for vWD types 2A, 2B, and 2M; unknown for other vWD subtypes.
Methodology:
Bidirectional sequencing of VWF exon 28 and its intron-exon boundaries.
Analytical Sensitivity and Specificity
: 99 percent.
Limitations
: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations, deep intronic mutations, and large deletion/duplications will not be detected. Mutations lying outside of VWF exon 28 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
CPT Code(s)
81403
Components
Component Test Code*Component Chart Name
2005487vWD2B (VWF) Specimen
2005488vWD Type 2B (VWF) Sequencing Interp
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, contact interface support at interface.support@aruplab.com.
Cross References
  • VWF2B Sequencing