Two novel mutations (Pro864His, Va1867Glu) causing type 2A von Willebrand disease and affecting a single restriction site in exon 28

We detected two transversions in two unrelated Italian patients with type 2 A von Willebrand disease (VWD): a C to A at nucleotide 8821 and a T to A at nucleotide 8830, resulting in the missense mutations Pro864His and Val867G lu respectively. Both mutations were in the heterozygous form and abolished the BstXI restriction site in exon 28 of the VWF gene. In both mutations p lasma VWF multimer pattern improved by antiproteases. Moreover, DDAVP norma lized plasma VWF multimers in the Pro864His patient, especially when protea se inhibitors were present. These new mutations appear to be of the 2A VWD subtype due to the increased susceptibility to proteases.