von Willebrand disease investigated by two novel RFLPs.

Two partial cDNAs for von Willebrand factor (vWF) were used to investigate gene lesions and restriction fragment length polymorphisms (RFLPs) in vW disease (vWd) and normal controls. No gene alteration was detected but two TaqI RFLPs, likely to be intronic and originating from point mutations, were found in the 3' part of vWF gene. The two TaqI RFLPs, identified by the same probe, are informative in approximately 50% of the subjects. Used in combination with two other known RFLPs, they define several haplotypes similarly distributed in vWd and normals. Linkage disequilibrium between loci identified by the RFLPs is present. In a family study the RFLP patterns demonstrate homozygosity for the affected vWF gene in a severe (type III) patient and identify several heterozygous subjects. The RFLPs analysis has been related to the haemostatic values and multimer distribution. In two of the four unrelated patients with severe vWd examined the RFLPs study indicates double heterozygosity for the affected vWF genes.