Von Willebrand Disease (VWD) Evaluation
| Also Known as (Alias) | VWD Genotyping |
| Method | Polymerase Chain Reaction (PCR) Based, Sanger sequencing |
| Test Information | Von Willebrand Disease (VWD) is one of the most common inherited bleeding disorders. This disorder is divided into three types, Type 1, Type 2 and Type 3. All types of this condition cause prolonged bleeding episodes of varying severity; Type 1 is the mildest of the three types and Type 3 is the most severe. Type 2 is intermediate in severity and is further divided into four subtypes. Type 2A VWD is the most common form of Type 2, accounting for 70% of the Type 2 diagnosis.
In type 1 and type 3 VWD, causative variants can be found throughout the gene. In type 2 VWD, generally (but not always) causative variants are located in a specific region of the gene that encodes a protein domain responsible for the specific VWF function that it is defective. Variants in the von Willebrand Factor (VWF) gene cause VWD. This disease can have different inheritance patterns. Type 1 and Type 2 (2A, 2B, and 2M) are inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Type 3 and Type 2N are inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. Reference for guidelines and mutation database: ASH ISTH NHF WFH 2021 guidelines on the diagnosis of Von Willebrand Disease |
| Additional Test Information | The VWD Evaluation sequences all 52 exons by Sanger sequencing. Confirmation is performed on a separate aliquot of DNA and Sanger sequenced. If necessary, Multiplex Ligation-dependent Probe Amplification (MLPA) is performed. |
| Sample Requirements | EDTA (lavender top) or extracted DNA |
| Requested Volume | 3-10cc EDTA (lavender top) tube or >10 ug extracted DNA at a concentration of >25ng/ul.
Analysis of amniocytes can be performed on cultured amniocytes. Two T-25 flasks of cells cultured to confluency will be accepted. Bloodworks Northwest does not have facilities to culture amniocytes. |
| Shipping Information | Whole blood shipped at ambient temperature (or on dry ice) and should arrive in the lab within 48 hours of the blood draw.
Send whole blood samples to: Cultured amniocyte samples shipped at ambient temperature and should arrive in the lab within 48 hours and received Tuesday through Thursday. Send cultured amniocyte samples to: Do not send samples to arrive on weekends or federal holidays or after 1pm on Fridays For additional information, please see Ordering Information-Bleeding Disorders |
| Requisition Form | Request for Testing Eastlake Bleeding Disorders Laboratory |
| Transaction Code | 3250-17 |
| CPT Codes | 81408 |
| Turn around Time (analytic time) | 2-4 weeks. If Multiplex Ligation-dependent Probe Amplification (MLPA) testing is necessary, it may take up to a couple of months. |
| Report/Results | Reports will be faxed or emailed. |
