PRACTICAL APPLICATION OF 3 POLYMORPHIC MICROSATELLITES IN INTRON 40 OF THE HUMAN VON-WILLEBRAND-FACTOR GENE

Intron 40 of the human von Willebrand factor gene contains a region wi th variable-number tandem repeats (VNTR), type (ATCT)(n), showing leng th polymorphism. In order to carry out family studies of von Willebran d's disease, we performed PCR procedures to analyze 3 previously descr ibed microsatellites from that region, both in normal individuals and in von Willebrand disease patients. Three pairs of primers were used t o amplify independently nucleotides 1890-1991 (VNTR 1), 2215-2380 (VNT R 2) and 1640-1794 (VNTR 3) from intron 40. The observed heterozygosit ies (0.75, 0.73 and 0.86 for VNTRs 1, 2 and 3, respectively) were in g ood agreement with the expected heterozygosities derived from the alle le frequencies (0.70, 0.73 and 0.79, respectively). Furthermore, the c ombination of the 3 VNTRs showed 96% of heterozygosity, which correspo nd with the 98% expected value under linkage equilibrium. Therefore, o ur conclusion is that the use of these 3 markers, especially VNTR 3, c onstitutes a rapid and reliable method for performing segregation stud ies in von Willebrand disease families.