A COMPARISON OF THE ALLELIC FREQUENCIES OF 10 DNA POLYMORPHISMS ASSOCIATED WITH FACTOR-VIII AND FACTOR-IX GENES IN THAI AND WESTERN-EUROPEAN POPULATIONS

The frequency of five factor VIII gene intragenic and linked DNA polym orphisms and five factor IX gene intragenic polymorphisms was studied in Thai females. The polymorphisms in the FVIII gene were detected by restriction enzymes BclI, XbaI, BglI. and at linked loci DX13 (DXS15) and St14 (DXS52) by BglII and TaqI, respectively, and in the FIX gene by MseI, DdeI, XmnI, TaqI and HhaI. With the exception of the BglI res triction fragment length polymorphism (RFLP), which is absent in Thais , factor VIII polymorphism frequencies were similar in Thais and Cauca sians. Combined use of XbaI and TaqI/St14 resulted in a heterozygosity rate of greater than 90% in Thai females. For FIX, the recently descr ibed MseI RFLP in the 5' flanking region was the most informative poly morphism in Thais, 43% of females being heterozygous. The other four p olymorphisms added little to the overall heterozygosity rate. The appr opriate polymorphisms were used to track defective factor VIII and IX genes through 22 Thai pedigrees with haemophilia to enable carrier sta tus to be assigned to female family members. The information obtained during this study will form the basis for carrier detection and prenat al diagnosis of haemophilia A and B by DNA polymorphism analysis in Th ailand.