Severe Type I 11 von Willebrand ’ s Disease Caused by Deletion of Exon 42 of the von Willebrand Factor Gene : Family Studies That Identify Carriers of the Condition and a Compound Heterozygous Individual

Southern blotting was performed with cDNA probes for the human von Willebrand factor (vWF) gene on six patients with severe type 111 von Willebrand’s disease (vWD). A partial deletion in the 3‘ end of the vWF gene was demonstrated in one individual whose parents were related and who had an alloantibody inhibitor to vWF. A resulting novel 2.0-kilobase (kb) EcoRl fragment was used for carrier detection within the patient’s family, and seven carriers of this recessive trait were identified. Of the six tested, five had normal or only slightly reduced levels of vWF antigen, but with generally higher levels of factor VIII. The sixth carrier had moderately severe vWD and it is