Korean J Lab Med.  2008 Aug;28(4):258-261. 10.3343/kjlm.2008.28.4.258.

A Case of Type 2N von Willebrand Disease with Homozygous R816W Mutation of the VWF Gene in a Nepalese Woman

• Lee SY
• Nam EM
• Lee SN
• Kim HJ
• Hong KS

• KMID: 854886
• DOI: http://doi.org/10.3343/kjlm.2008.28.4.258

Abstract

Type 2N von Willebrand disease (vWD) can be confused with hemophilia A due to decreased factor VIII levels and a bleeding tendency, and differential diagnosis is of importance for providing the optimal treatment and genetic counseling. For the accurate diagnosis of type 2N vWD, von Willebrand Factor (vWF) function tests, multimer assay and gene mutation analysis are needed. The patient was a 38-yr-old Nepalese woman with a history of bleeding manifestations from childhood, such as hemarthrosis, intramuscular hematoma, and menorrhagia. Family history revealed that her mother and elder brothers also had bleeding manifestations from childhood. When she had a laparotomy in 1991, she was diagnosed as hemophilia A with factor VIII level of 3.6% and was transfused with whole blood, factor VIII and cryoprecipitates. In June 2007, she was admitted to our hospital for further evaluation of bleeding tendency. Blood tests revealed normal CBC; bleeding time, 2 min; PT, 14.9 sec (11-14 sec); aPTT, 51.2 sec (24-38 sec); and factor VIII, 4.9% (50-150%). The prolonged aPTT was corrected by 1:1 mixing test to the levels of 106% and 84%, respectively, before and after 2 hr-incubation at 37degrees C. No abnormalities were found in the vWF antigen level (71.3%), ristocetin cofactor assay (130.4%), and multimer assay. Direct DNA sequencing of the VWF gene revealed homozygous missense mutation located in exon 19, c.2446C>T (p.Arg816Trp), confirming the diagnosis of type 2N vWD.

Keyword

Von Willebrand disease; Type 2N; R816W; Nepalese

MeSH Terms

Adult
Amino Acid Substitution
Asian Continental Ancestry Group/genetics
Base Sequence
Female
Genotype
Homozygote
Humans
Nepal
von Willebrand Disease/blood/*diagnosis/genetics
von Willebrand Factor/analysis/*genetics

Figure

• 

  Fig. 1. VWF gene mutation analysis by direct sequencing revealed that the patient was homozygous for a missense mutation, c.2446C>T (p. Arg816Trp), which is a known mutation causing von Willebrand disease, type 2N.

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