FACTOR-VIII GENE-MUTATIONS AND RFLP ANALYSIS IN HEMOPHILIA-A

Hemophilia A is an X-linked bleeding disorder caused by a quantitative or qualitative defect of coagulation factor VIII. Since factor VIII h as been cloned and several intragenic and linked DNA polymorphisms dis covered, DNA analysis is an accepted and commonly used method for carr ier testing in hemophilia A. Both a direct method using detection of m utation and an indirect method based on linkage between the disease an d DNA polymorphism are used for this purpose. In this study, DNA sampl es of 110 hemophilia A patients from 99 families were screened for fac tor VIII gene mutation using Southern blot analysis; in seven families , mutations were detected. In 13 females from six families with identi fied mutation, the direct diagnosis of carriers was performed. Four in tragenic (BalI, XbaI, BglI and MspI in F8C locus) and two linked polym orphisms (TaqI in DXS52 locus and BglII in DXS15 locus) were studied i n members of 47 hemophilia A families. Bali-XbaI-BglI haplotypes were analyzed in 90 unrelated X chromosomes. Eighteen out of 31 females (58 % were heterozygous for at least one intragenic polymorphism, and 29 o ut of 31 females (94%) were heterozygous for at least one intra- or ex tragenic polymorphism tested. Carrier diagnosis was made in 15 out of 25 possible carriers (60%) based on intragenic and in an additional 3 out of 25 (12%) only on linked polymorphism.