CARRIER DETECTION OF OVINE HEMOPHILIA-A USING AN RFLP MARKER, AND MAPPING OF THE FACTOR-VIII GENE ON THE OVINE X-CHROMOSOME

Ovine hemophilia A is an X-linked recessive bleeding disorder. For dia gnostic purposes, restriction fragment length polymorphism (RFLP) anal ysis in the region of the factor VIII (F-VIII) gene was carried out us ing human F-VIII gene probes. The probe St14, known to detect a highly polymorphic region that is closely linked to the F-VIII gene in human s, hybridized nonspecifically with DNA from sheep. Searching for intra genic RFLPs, the entire 9.0-kb coding sequence of the human F-VIII was used as a probe. Using the 1.8-kb SstI/KpnI F-VIII cDNA probe for hyb ridization, an Mspl-RFLP with allelic bands of 5.8 kb (A1) and 4.2 kb (A2) was detected. A1 was in linkage phase with the mutated allele res ponsible for hemophilia A. The F-VIII locus in the sheep genome was as signed to the long arm of the X-chromosome in the region Xq24-q33, usi ng in situ hybridization with a 3-kb human F-VIII cDNA probe to QFQ ba nded sheep metaphase chromosomes.