An alternative strategy for identification of type IIA VWD mutations

A 306 base pair segment of the von Willebrand's factor (VWF) gene between nucleotides 4627 and 4932 was amplified by PCR using DNA from a type IIA VWD patient. The amplified DNA was cloned in the plasmid pCRII. Clones of the VWF gene and pseudogene were distinguished by their KpnI restriction patterns. A series of six VWF gene clones was sequenced. A single C to T point mutation at nucleotide 4789 resulting in the substitution of arginine 834 by tryptophan was identified in four clones. This mutation, which destroys a BstEII restriction site, was also detected in amplified DNA of affected relatives of the patient. The method described avoids difficulties associated with strategies employed previously for identification of VWD mutations.