Patients with genetically confirmed von Willebrand disease (VWD) type 2M have a relatively mild clinical phenotype, according to findings from a retrospective cross-sectional study.

In fact, three of 31 patients included in the study had a near normal laboratory phenotype. Additionally, patients with the p.Val1360Ala mutation had significantly higher values of all von Willebrand factor (VWF)-related laboratory parameters, compared with those with the p.Arg1374Cys or p.Phe1293Leu mutation, Dominique Maas reported at the European Association for Haemophilia and Allied Disorders annual meeting.

The findings underscore the importance of genotyping for making a correct diagnosis of VWD type 2M, said Ms. Maas of Radboud University Medical Center, Nijmegen, The Netherlands.

The study subjects, who had a least one VWD type 2M mutation, had a median age of 34 years and a median bleeding score of 6. Most suffered from mucocutaneous bleeding, but with low frequency compared with other VWD subtypes. The incidence of muscle hematomas, postpartum hemorrhage, and postsurgery bleeding were relatively high, however. Age and bleeding score were strongly positively correlated.

Subjects had a median VWF antigen level of 24 IU dL-1, median VWF ristocetin cofactor activity of 6 IU dL-1, and median VSF:RCo/VWF:Ag ratio of 0.29. The VSF collagen binding activity and VWF:Ag ratio was normal, she said.

Genotyping is a powerful diagnostic tool for making an appropriate diagnosis and classification of VWD. The current findings are important because understanding the correlation between genotype and phenotype improves the understanding of VWD pathogenesis and has important implications for treatment, follow-up, and genetic counseling, but has not been throughly investigated in fully genotyped patients with VWD type 2M, she said.

Ms. Maas reported having no disclosures.


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