title: Severe Hemophilia A in a Male Old English Sheep Dog with a C→T Transition that Created a Premature Stop Codon in Factor VIII.
abstract: Animals with hemophilia are models for gene therapy, factor replacement, and inhibitor development in humans. We have actively sought dogs with severe hemophilia A that have novel factor VIII mutations unlike the previously described factor VIII intron 22 inversion. A male Old English Sheepdog with recurrent soft-tissue hemorrhage and hemarthrosis was diagnosed with severe hemophilia A (factor VIII activity less than 1% of normal). We purified genomic DNA from this dog and ruled out the common intron 22 inversion; we then sequenced all 26 exons. Comparing the results with the normal canine factor VIII sequence revealed a C→T transition in exon 12 of the factor VIII gene that created a premature stop codon at amino acid 577 in the A2 domain of the protein. In addition, 2 previously described polymorphisms that do not cause hemophilia were present at amino acids 909 and 1184. The hemophilia mutation creates a new TaqI site that facilitates rapid genotyping of affected offspring by PCR and restriction endonuclease analyses. This mutation is analogous to the previously described human factor VIII mutation at Arg583, which likewise is a CpG dinucleotide transition causing a premature stop codon in exon 12. Thus far, despite extensive treatment with factor VIII, this dog has not developed neutralizing antibodies ('inhibitors') to the protein. This novel mutation in a dog gives rise to severe hemophilia A analogous to a mutation seen in humans. This model will be useful for studies of the treatment of hemophilia.
authors: Department of Laboratory Medicine, National Institutes of Health Clinical Center, Bethesda, Maryland, USA.
authors: Jay N
authors: JN
authors: Lozier
authors: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors: Mark T
authors: MT
authors: Kloos
authors: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors: Elizabeth P
authors: EP
authors: Merricks
authors: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors: Nathaly
authors: N
authors: Lemoine
authors: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors: Margaret H
authors: MH
authors: Whitford
authors: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors: Robin A
authors: RA
authors: Raymer
authors: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors: Dwight A
authors: DA
authors: Bellinger
authors: Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. tnichols@med.unc.edu.
authors: Timothy C
authors: TC
authors: Nichols
mesh_terms: D000818:Animals; D018388:Codon, Terminator; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs / Q000097:blood / Q000235:genetics*; D005169:Factor VIII / Q000235:genetics*; D006467:Hemophilia A / Q000235:genetics / Q000662:veterinary*; D017354:Point Mutation; D017422:Sequence Analysis, DNA / Q000662:veterinary
chemical_list: D018388:Codon, Terminator; D005169:Factor VIII