Abstract
We previously reported that the reduced normal plasma von Willebrand factor (vWF) consists of 240, 216 (220, 210), 194, 164, and 144 kDa fragments. We also described a new 200kDa reduced fragment in addition to those of normal plasma vWF in two patients with type I b von Willebrand disease (vWD). In one (T. O.) of the two families, a similar 200 kDa reduced fragment is herein reported in the proband's mother and daughter who showed abnormal laboratory findings without bleeding symptoms. This study highly suggested that they could be the heterozygotes for a mutant gene.
The abnormal 200kDa fragment reacted with both of the anti-reduced SPIII and SPII antibodies. The products of digestion by V-8 protease indicated an abnormal 80kDa fragment in addition to those of normal plasma vWF. This 80kDa fragment reacted with only the anti-reduced SPIII antibody, but not the anti-reduced SPIT antibody. These results suggested that the mutation localized on the C-terminal region of the SPIII fragment of vWF subunit.
