Case Study#5   1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16   Summary Clinical history and laboratory data consistent with von Willebrand disease, type II (lack of larger multimers) No family history 2 of 5 children tested negative for vWD No bleeding history until age 72 Acquired vWD First described in 1970's Estimated prevalence 0.04 - 0.13%, fewer than 300 cases reported Usually encountered in adults with no personal or family bleeding history Laboratory work-up most consistent with Type II vWD Acquired vWD: Pathophysiology An antibody to vWF is often present but, unlike other inhibitors, the Ab does NOT bind a functional site to prevent action; instead, the Ab increases clearance of HMWM (fig B) by RES, causing depletion of HMWM (fig C); mixing with normal plasma corrects ristocetin activity