NEW POLYMORPHIC VARIANTS OF HUMAN BLOOD-C LOTTING FACTOR-IX

The polymorphism of Alu-repeats, which are located in the introns of t he human factor IX gene (copies 1 - 3), was studied. To identify polym orphic variants, direct sequencing of PCR products that contained appr opriate repeats was used. In each case, 20 unrelated X chromosomes wer e studied. A polymorphic Dra I site was found near the 3'-end of Alu c opy 3 within the region of the polyA tract. A PCR-based testing system with internal control of restriction hydrolysis was suggested. Testin g 81 unrelated X chromosomes revealed that the frequency of the polymo rphic Dra I site is 0.23. Tag I polymorphism, which was revealed in Al u copy 4 of factor M. gene in our previous work, was found to be close ly linked to Dra I polymorphism. Studies in linkage between different types of polymorphisms of the factor IX-gene revealed the presence of a rare polymorphism in intron A that was located within the same minis atellite region as the known polymorphic insertion 50bp/Dde I. However , the size of the insertion in our case was 26 bp. Only one polymorphi c variant was found among over 150 unrelated X chromosomes derived fro m humans from Moscow and its vicinity.