DNA von Willebrand Disease Type 2N
| Also Known as (Alias) | VWF Genotyping Screen, Type 2N VWD |
| Method | Polymerase Chain Reaction (PCR) Based |
| 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 defined by a partial quantitative VWF deficiency, while Type 3 is defined by the absence of detectable VWF. Type 1C is defined by low VWF levels and rapid VWF clearance. Type 2 is defined by a functional (qualitative) VWF defect 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.
Type 2N VWD is defined by low coagulation factor VIII (FVIII) levels due to a defect in the ability of VWF to bind FVIII. Nearly all variants that cause Type 2N VWD are located in the exons that encode VWF D’-D3 region. Some type 2N variants affect the VWF propeptide. Variants in the von Willebrand Factor (VWF) gene cause VWD. This disease can have different inheritance patterns. Type 1, Type 1C, and Type 2 (2A, 2B, and 2M) are generally 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 variants. Reference for guidelines and mutation database: ASH ISTH NHF WFH 2021 guidelines on the diagnosis of Von Willebrand Disease |
| Additional Test Information | This Von Willebrand Factor Type 2N VWD Screen sequences exons 4, 9, 18-21, 24, 25,& 27.
If a causative pathogenic variant is not identified, further screening can be performed by the DNA Von Willebrand Disease Evaluation. Confirmation is performed by sequencing the exon(s) in which the variant(s) is/are located. |
| 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 | 3250-09 |
| CPT Codes | 81408 |
| Turn around Time (analytic time) | 5-10 business days |
| Report/Results | Reports will be faxed or emailed. |
