Type 2A is a qualitative variant of von Willebrand disease (vWD) characterized by a reduced platelet-dependent function, associated with an absence of large multimers. A G5135A transition, resulting in a glycine to arginine substitution at the codon 1629 of the von Willebrand factor, was identified by automated sequencing in one type 2A vWD Spanish patient. To detect this new candidate mutation a modified primer that creates a Ddel restriction site when the mutation is present was designed. This approach allowed detection of the mutation in the other three patients from the same family. On the other hand, the fact that this new mutation was not found in the 110 normal alleles screened further supports their causal relationship with the disease.