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The continued review of breed-specific tests for assigning relevancy ratings, and ongoing discussions with genetic experts has led to a refinement of the breed relevancy ratings (please see: BRR) . To better accommodate the spectrum of genetic test validation, we’ve added a new orange BRR. The orange BRR indicates where all current available evidence has been reviewed, but the relevancy is inconclusive. It could be that a mutation is detectable in a specific breed, but that there is no evidence that this correlates with clinical development of the disease/phene. It could also be that there is evidence that testing for the mutation does not correlate with the clinical development of the disease. One example is the wire-fox terrier and degenerative myelopathy. Despite research indicating a 94% mutation frequency (Zeng et. al, 2014) - meaning that practically every dog the researchers tested for SOD 1 mutation for degenerative myelopathy had 2 copies of the mutation - the development of the clinical signs of DM for the breed hasn't yet been reported. In practical terms, this means that while you may still wish to test for the mutation in your breed, or it may be included on any testing panels, there isn’t currently a good reason to prioritize test results in any breeding or other health decisions. Unnecessarily excluding a dog from breeding based on irrelevant or inconclusive test results can be, on balance, very damaging to the genetic diversity of the breed. Thinking back to DM and the wire-fox terrier, this would mean that if breeding decisions were made on DM test results alone, you'd be excluding the vast majority of the dog population where the test does not for this breed seem to predict clinical disease. For any orange BRR, it would be worth looking at the test’s breed-specific information in more detail (search for test information HERE) to help put any potential test results into perspective. Wherever possible, the phenes database includes comments directly from the researchers and original test developers. As always, talk to your genetic test provider and/or veterinary scientist if you are concerned about genetic test results. And, if you missed it the first time around, you may want to check out the previous blog including updated breed relevancy ratings, and breed-specific publications, HERE. References: Zeng R., Coates J.R., Johnson G.C., Hansen L., Awano T., Kolicheski A., Ivansson E., Perloski M., Lindblad-Toh K., O'Brien D.P., Guo J., Katz M.L., Johnson G.S. (2014) Breed Distribution of SOD1 Alleles Previously Associated with Canine Degenerative Myelopathy. J Vet Intern Med 28: 515-521 Photo thanks to: Engin Akyurt, via Pexels
A recent article provided by the Golden Retriever Club of America, Golden Retriever Health and Genetics Highlight: Neuronal Ceroid Lipofuscinosis in Golden Retrievers, by Ann Hubbs and Ron Rubrecht,, discussed the challenges faced in Fall 2018, by a breeder who had unsuspectingly bred a litter of puppies from two carriers of neuronal ceroid lipofuscinosis (NCL 5) – a devastating neurological disease considered rare in the breed. While a DNA test existed, most Golden Retriever owners wouldn’t be aware of the condition, let alone testing options. The breeder did the absolute right thing when realizing there was a problem, by working swiftly to genetically test their dogs, contacting owners, and working with the Breed Club to make other breeders aware of the risks of NCL 5. The situation for this breeder could arise for various conditions in many breeds. Inherited diseases that are generally rare in a breed are unlikely to be considered in selection by breeders. It could be that a genetic test isn’t available, or that it is not a priority for testing compared to more common inherited risks, or, increasingly, it might be a well-known condition in a breed in one country, but less known internationally. This is understandable, especially considering that the risks of an inherited disease in the breed as a whole, is not necessarily reflective of the risks for the breeding population. (Fig 1.) The dogs who are left intact and used in breeding, particularly by Show/Field breeders, is only a tiny percentage of the dogs making up the whole breed. It is easy to imagine how a few popular dogs who happen to be genetic carriers [See 'carrier' defined in glossary for AR inheritance] for a rare disease like NCL 5, could shift the risks of inheritance within a few generations without anyone realizing that there is a problem at all. For NCL 5 in the Golden Retrievers, fortunately, there is a genetic test available that can identify those dogs who are clear, carrier, or genetically affected for the condition. This will be especially valuable for those specific breeding lines within which the disease has occurred or is suspected. However, it is important to put into perspective how concerning NCL 5 is for the breed, relative to other important factors, in order to be sure that breeding decisions are made sensibly across all the considerations when making breeding plans. Currently, within a US population tested by Embark, only <1% of the dogs tested are carriers of the NCL 5 mutation. This is known as carrier frequency. At this level of carrier frequency, breeders can develop breeding plans that include clear and carrier tested dogs, to efficiently breed away from the mutation risk, without causing a genetic bottleneck or producing genetically affected puppies. It is important for a disease like NCL, which is still likely to be clinically rare in the breed, to breed away steadily to balance any other inherited risks, as well as allowing selection for positive characteristics. Avoiding a knee-jerk reaction will help to ensure that future generations have a greater variety of breeding lines to choose from. IPFD is continuing to develop plans for the Health Strategies Database for Dogs that aims to catalog all conditions that are being addressed by those designing breed-specific health programs around the world, especially kennel and breed clubs. See “Get a GRIHP on Breed Health” - Breed Health Strategies Presentation given by Brenda Bonnett at the 4th International Dog Health Workshop. What’s a GRIHP? Globally Relevant Integrated Health Profile... https://dogwellnet.com/files/file/422-4th-idhw-breed-specific-health-strategies-dogwellnet-resources-brenda-bonnett/ Additional information HGTD has a number of resources to help breeders and owners make informed decisions on genetic testing. You can search for genetic test providers, breed-specific diseases, and more information on tests/diseases HERE. Recently, HGTD has launched relevancy ratings for many of the tests that the participating genetic test providers are offering. Using data and information from researchers, test providers, kennel and breed clubs, and veterinary scientists, relevancy ratings are a way of indicating all of the currently known research material on a specific test for a specific breed. Additional information University of Missouri - Golden NCL: http://www.caninegeneticdiseases.net/GoldenNCL/ The Orthopedic Foundation for Animals records the NCL5 test results for Goldens - search at https://www.ofa.org/diseases/breed-statistics. Also see further information on Neuronal Ceroid Lipofuscinosis at OFA: https://www.ofa.org/diseases/dna-tested-diseases/neuronal-ceroid-lipofuscinosis. Research The NCL 5 mutation origin paper: Melville, SA., Wilson, CL., Chiang, CS., Studdert, VP., Lingaas, F., Wilton, AN. : A mutation in canine CLN5 causes neuronal ceroid lipofuscinosis in Border collie dogs. Genomics 86:287-94, 2005. Pubmed reference: 16033706. DOI: 10.1016/j.ygeno.2005.06.005. 2019 Villani, N.A., Bullock, G., Michaels, J.R., Yamato, O., O'Brien, D.P., Mhlanga-Mutangadura, T., Johnson, G.S., Katz, M.L. : A mixed breed dog with neuronal ceroid lipofuscinosis is homozygous for a CLN5 nonsense mutation previously identified in Border Collies and Australian Cattle Dogs. Mol Genet Metab 127:107-115, 2019. Pubmed reference: 31101435. DOI: 10.1016/j.ymgme.2019.04.003. 2017 Katz, M.L., Rustad, E., Robinson, G.O., Whiting, R.E.H., Student, J.T., Coates, J.R., Narfstrom, K. : Canine neuronal ceroid lipofuscinoses: Promising models for preclinical testing of therapeutic interventions. Neurobiol Dis :, 2017. Pubmed reference: 28860089. DOI: 10.1016/j.nbd.2017.08.017. 2016 Kolicheski, A., Johnson, G.S., O'Brien, D.P., Mhlanga-Mutangadura, T., Gilliam, D., Guo, J., Anderson-Sieg, T.D., Schnabel, R.D., Taylor, J.F., Lebowitz, A., Swanson, B., Hicks, D., Niman, Z.E., Wininger, F.A., Carpentier, M.C., Katz, M.L. : Australian Cattle Dogs with Neuronal Ceroid Lipofuscinosis are Homozygous for a CLN5 Nonsense Mutation Previously Identified in Border Collies. J Vet Intern Med :, 2016. Pubmed reference: 27203721. DOI: 10.1111/jvim.13971. Mizukami, K., Yabuki, A., Kohyama, M., Kushida, K., Rahman, M.M., Uddin, M.M., Sawa, M., Yamato, O. : Molecular prevalence of multiple genetic disorders in Border collies in Japan and recommendations for genetic counselling. Vet J 214:21-3, 2016. Pubmed reference: 27387721. DOI: 10.1016/j.tvjl.2016.05.004. 2015 Gilliam, D., Kolicheski, A., Johnson, G.S., Mhlanga-Mutangadura, T., Taylor, J.F., Schnabel, R.D., Katz, M.L. : Golden Retriever dogs with neuronal ceroid lipofuscinosis have a two-base-pair deletion and frameshift in CLN5. Mol Genet Metab 115:101-9, 2015. Pubmed reference: 25934231. DOI: 10.1016/j.ymgme.2015.04.001. 2013 Bond, M., Holthaus, S.M., Tammen, I., Tear, G., Russell, C. : Use of model organisms for the study of neuronal ceroid lipofuscinosis. Biochim Biophys Acta 1832:1842-65, 2013. Pubmed reference: 23338040. DOI: 10.1016/j.bbadis.2013.01.009. 2012 Mizukami, K., Kawamichi, T., Koie, H., Tamura, S., Matsunaga, S., Imamoto, S., Saito, M., Hasegawa, D., Matsuki, N., Tamahara, S., Sato, S., Yabuki, A., Chang, H.S., Yamato, O. : Neuronal ceroid lipofuscinosis in Border Collie dogs in Japan: clinical and molecular epidemiological study (2000-2011). ScientificWorldJournal 2012:383174, 2012. Pubmed reference: 22919312. DOI: 10.1100/2012/383174. 2011 Mizukami, K., Chang, H.S., Yabuki, A., Kawamichi, T., Kawahara, N., Hayashi, D., Hossain, M.A., Rahman, M.M., Uddin, M.M., Yamato, O. : Novel rapid genotyping assays for neuronal ceroid lipofuscinosis in Border Collie dogs and high frequency of the mutant allele in Japan. J Vet Diagn Invest 23:1131-9,
3 downloadsOculoskeletal dysplasia • Canine genetics research at the Animal Health Trust • Basic genetics • Finding disease mutations • Genetics of OSD – Part 1 – Identifying the causal mutation • Genetics of OSD – Part 2 – Implications for the breed • Summary and Breeding Advice • Acknowledgements • OSD3 DNA Test Breeds information/impacts... - the drd1 mutation in the gene COL9A3 in the Labrador retriever - the drd2 mutation in the gene COL9A2 in the Samoyed - autosomal recessive mode of inheritance of the complete phenotype • Clinical findings in the Labrador retriever & in the Samoyed (Carrig et al. 1988 & Goldstein et al. 2010) - disproportionate dwarfism - corneal opacities, cataracts, persistent hyaloid artery remnants, vitreal dysplasia, alterations in optic nerve head colour + size, retinal dysplasia retinal detachment • Recently observed in 7 Northern Inuit Dogs (NID)