In the February 2007 issue of the Journal of Thrombosis and Haemostasis, a team of
scientists reported the discovery of two areas in the mouse genome that may explain
about 45% of the genetic variation of plasma levels of von Willebrand factor (VWF) in
mice. The researchers include Jordan Shavit, MD, PhD, current NHF Clinical Fellow at
the University of Michigan, Ann Arbor, and researchers from Johns Hopkins University
in Baltimore, MD, and the Howard Hughes Medical Institute in Chevy Chase, MD. VWF
is an important protein that interacts with other blood proteins to form blood clots.
Deficiencies of VWF in the blood result in von Willebrand disease (VWD), the most
prevalent inherited bleeding disorder in the world.
Unlike monogenetic disorders, which are caused by the mutation or absence of a single
gene, such as hemophilia, VWD is a polygenic disorder, one that is affected by the
interplay of several different genes. Its genetic inheritance is complex, and remains a
mystery that scientists are still trying to unravel. Researchers have yet to determine the
genes responsible for the severity of VWD and its variation within an individual’s genetic
According to the study, the scientists discovered two areas in the mouse’s genetic
makeup--called Mvwf3 and Mvwf4--that contribute to the genetic expression of plasma
VWF. The report showed that a combined effect of the two can explain up to 45% of the
variation of plasma VWF in light of their interaction with a third area, Mvwf2. This
finding is significant because previous studies could only explain 20%-30% of VWF
variation in blood plasma.
The scientists speculate that further research on Mvwf3 and Mvwf4 will help identify
other important modifier genes that contribute to the clinical expression of VWD. This
study represents important progress toward a better understanding of the genetics of
VWF and VWD. Using a mouse model is feasible for gaining a better understanding of
VWD in humans because they share similar genes for VWF.
Source: Lemmerhirt, HL, KW Broman, JA Shavit, et al. “Genetic Regulation of Plasma
von Willebrand Factor Levels: Quantitative Trait Loci Analysis in a Mouse Model.”
Journal of Thrombosis and Haemostasis. 2007; 5(2): 329-335.