The goal was the discovery of mutations in coagulation Factor VIII that cause hemophilia A (Factor VIII deficiency) in Golden retrievers. The results at the end of the grant indicated that several distinct mutations in the Factor VIII gene cause hemophilia in this breed. The phenomenon of different Factor VIII mutations arising in different families is well-documented in human beings, and is likely true for all canine breed populations. The researchers identified an abnormal DNA sequence in the Factor VIII gene of a Golden retriever with severe hemophilia and are completing experiments to confirm that this variation is the causative mutation. They have not yet discovered the mutation responsible for a milder form of hemophilia in Golden retrievers. They suspect that the mutation in this mild form will be found in a region of the gene involved in protein stability or processing and will therefore involve examination of large portions of the gene, rather than targeted evaluation of a few functional sites. Pending discovery of hemophilia-causing mutations, an alternate strategy based on gene tracking may be useful to identify suspect carriers in some cases. Gene tracking requires samples from key family members (affected male and dam, siblings). Please contact the Dr. Brooks at the Coagulation Laboratory at Cornell University if you would like to discuss a specific case.