Type IIB von Willebrand's disease with probable autosomal recessive inheritance and presenting as thrombocytopenia in infancy.

von Willebrand's disease (vWD) is a congenital bleeding disorder that exists in two main forms. In the classic form, type I, the concentration of the von Willebrand factor (vWF) in plasma is decreased. In type II vWD, the vWF is structurally altered. Type II can be further divided into at least six subtypes (A, B, C, D, E and F). In type IIB the vWF, in contrast to other variants of vWD, shows an increased affinity for platelets. IIB vWD is generally believed to be inherited in an autosomal dominant manner. We describe two families with three affected children in whom an autosomal recessive inheritance is more likely. Thrombocytopenia, constant or variable, was present from early infancy in all three cases. Type IIB vWD should thus be included in the differential diagnosis of congenital thrombocytopenia.