Collie Eye Anomaly (CEA/CH)
Collie Eye Anomaly (CEA/CH)
Disease Name 2
CEA, Collie Eye Anomaly
CEA/CH causes abnormal development of the choroid - an important layer of tissue under the retina of the eye. Since the choroid layer does not develop normally from the start, the primary abnormality can be diagnosed at a very young age by an opthamologist. The clinical effects vary greatly among affected dogs within one breed, between parent and offspring and even within a litter. Most often the disease presents as a mild form in affected dogs and the presence of the disease can only be detected upon ophthalmologic examination; the dog retains normal vision throughout life. However, dogs with mild disease can produce severely affected offspring. The severe forms can result in serious vision loss or blindness in some cases. Inheritance of CEA/CH is approximately autosomal recessive. In some cases, the phenotype can vary to include colobomas and staphylomas in the optic nerve head and adjacent tissues ? which may be the only visible abnormality. This has led to some adult dogs in this category being termed so-called ?go normals?. The term ?go normal? has been applied to cases where post-natal development obscures the choroidal hypoplasia which is the key diagnostic feature, so that adult dogs have ?normal? appearance despite being genotypically affected. The phenomenon is common enough that many ophthalmologists recommend clinical examination to be focused on puppies/young dogs. This suggests other factors may have an effect on CEA/CH expression, i.e. that the disorder is multifactorial.
Collie eye anomaly (CEA) is a congenital, inherited ocular disorder affecting retinal, choroidal, and scleral development, which is widespread in herding breeds. Clinically, the two major lesions associated with CEA are choroidal hypoplasia (CH) and coloboma, and both lesions are diagnosed based on ophthalmological examination. However, in addition to choroidal hypoplasia, colobomas and staphylomas of the optic nerve head and adjacent tissues are considered part of the extended phenotype and can be the only visible abnormality - particularly as the dog ages. Given the challenges of diagnosis, many ophthalmologists recommend a clinical eye examination as early as possible (ie at five to six weeks of age), so that it is diagnosed clinically with greatest accuracy. Breeding advice for removing this disease from a breed tends to recommend a combined effort of litter screening (to identify clinically affected dogs), with DNA testing (for aid in breeding planning/prediction).
Patents: Cornell Research Foundation, Inc. Licenses: Optigen - US, CA, Europe. (please note that patent and licensing laws and coverage vary by country)
Parker, H.G., Kukekova, A.V., Akey, D.T., Goldstein, O., Kirkness, E.F., Baysac, K.C., Mosher, D.S., Aguirre, G.D., Acland, G.M., Ostrander, E.A. : Breed relationships facilitate fine-mapping studies: a 7.8-kb deletion cosegregates with Collie eye anomaly across multiple dog breeds. Genome Res 17:1562-71, 2007. Pubmed reference: 17916641. DOI: 10.1101/gr.6772807
Lowe, JK., Kukekova, AV., Kirkness, EF., Langlois, MC., Aguirre, GD., Acland, GM., Ostrander, EA. : Linkage mapping of the primary disease locus for collie eye anomaly. Genomics 82:86-95, 2003. Pubmed reference: 12809679.
Brown, E.A., Thomasy, S.M., Murphy, C.J., Bannasch, D.L. :Genetic analysis of optic nerve head coloboma in the Nova Scotia Duck Tolling Retriever identifies discordance with the NHEJ1 intronic deletion (collie eye anomaly mutation). Vet Ophthalmol :, 2017. Pubmed reference: 28702949. DOI: 10.1111/vop.12488.
Fredholm, M., Larsen, R.C., Jönsson, M., Söderlund, M.A., Hardon, T., Proschowsky, H.F. : Discrepancy in compliance between the clinical and genetic diagnosis of choroidal hypoplasia in Danish Rough Collies and Shetland Sheepdogs. Anim Genet 47:250-2, 2016. Pubmed reference: 26732749. DOI: 10.1111/age.12405.
Gene Name Text
nonhomologous end-joining factor 1