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Principal Investigator: Marjory Brooks
Contact Information: E-mail: mbb9@cornell.edu - Phone: 607-275-0622
Sponsor: American Kennel Club Canine Health Foundation
Grant Number: ACORN No. 1185
Title: Hemophilia A in Golden Retrievers -Search for the Causative Mutation
Annual Direct Cost: $11,650
Project Period: 08/01/08 - 07/31/09
DESCRIPTION (provided by applicant): This study aims to discover a mutation causative for Hemophilia A in Golden Retrievers, with the ultimate goal of developing an accurate carrier detection test. Hemophilia A (Factor VIII deficiency) is a mutationally heterogeneous, X-linked recessive trait. A clinically moderate form of hemophilia has become disseminated in Golden retrievers, propagated by affected males and carrier females. Although measurement of plasma Factor VIII activity accurately identifies affected dogs, these assays are unable to differentiate carrier from clear females. Our previous study indicated that segregation analyses based on Factor VIII marker genotyping was feasible in this breed. The limitations inherent to indirect carrier detection, however, precluded broad application of this strategy and new cases have been diagnosed recently. In the proposed study we will first perform a series of reverse transcription PCR (rtPCR) experiments to screen for the presence of a mutant Factor VIII transcript in hemophilic males. We will then use a directed sequencing strategy to define the genomic mutation responsible for the aberrant transcript. In the absence of abnormal cDNA, we will screen genomic DNA from affected males for mutations by sequencing amplicons spanning the promoter region, exons, and intron-exon junctions of the Factor VIII gene.
Hemophilia A is an inherited bleeding disorder that affects many different breeds of dog. The disease is caused by mutations in coagulation Factor VIII (Factor 8), a critical blood protein required for normal blood clot formation. Hemophilia A is an X-linked trait that manifests as a bleeding tendency in males, whereas females are asymptomatic carriers. Hemophilia A has been recognized recently in Golden Retrievers, with evidence of transmission of the trait through more
than 7 generations. Affected males are typically diagnosed because of prolonged post-operative and post-traumatic bleeding. Although many dogs respond to transfusion, some dogs experience recurrent bleeds, and some have been euthanized due to poor quality of life. The dog genome provides an invaluable tool to identify disease-causing mutations that underlie genetic defects in
dogs. Our proposed project aims to discover the mutation that causes Hemophilia A in Golden Retrievers in order to develop a carrier detection assay. This project builds on a previous study that developed a preliminary "gene tracking" technique to identify carrier females. A mutation detection test will overcome the limitations of gene tracking methods and provide the most accurate assay, with broadest applicability to prevent any further propagation of Hemophilia A in
this breed.
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