A -793 G TO A TRANSITION IN THE FACTOR-IX GENE PROMOTER IS POLYMORPHIC IN THE CAUCASIAN POPULATION

We report the incidence of a prevalent polymorphism at position -793 i n the promoter region of the factor IX gene in caucasian individuals. This DNA change was originally reported as one of two changes in the f actor IX gene of a severely affected haemophilia B patient from Japan. We confirm the neutral nature of this change and demonstrate that, de spite showing linkage disequilibrium with the previously reported MseI RFLP <100 bp distant, the use of these two loci together in a carrier screening strategy significantly increases the level of informativity over that achieved using either polymorphism alone.