Hemostasis Reference Laboratory

DNA Von Willebrand Disease Type 2A/2B 2N

Transaction code: 3250-08

CPT codes (suggested): 83890, 83898, 83909, 83904 (x3), 83892, 83894, 83912

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.

Mutations 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.

Method
The Von Willebrand Factor Screen sequences up to 9 exons for mutations depending on the type. Confirmation is performed one of two ways. If the mutation creates/removes a restriction enzyme digestion site, the testing will be performed by RFLP. If a restriction enzyme digestion site is not present, testing will be done by sequencing the exon in which the mutation is located.

Test Details

Turnaround Time: Von Willebrand mutation testing takes 2-4 weeks. If the mutation is known, screening for family members takes 1-2 weeks.

Sample Requirements: 5-10mL whole blood drawn in EDTA and shipped at 4°C or ambient temperature is acceptable. Refer to the sample requirements page for more information on shipping.

Analysis of amniocytes can be performed on cultured amniocytes. Two T-25 flasks of cells cultured to confluency will be accepted. Puget Sound Blood Center does not have facilities to culture amniocytes.