Collie eye anomaly (CEA Dog)
Collie eye anomaly (CEA) is a developmental disorder of the eye characterised by choroidal hypoplasia (underdevelopment) and can lead to blindness in severe cases.
The disease occurs in Collie, Border Collie, Australian Shepherd and Shetland Sheepdog. The inheritance is autosomal recessive.
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Symptoms
- Visual defect
- Detachment of the retina
- In severe cases blindness
General Information
- Collie eye anomaly (CEA) is a complex developmental disorder of the posterior segment of the eye.
- It is characterised by choroidal hypoplasia (underdevelopment).
- The choroid is located between the sclera and the retina in the posterior half of the eyeball.
- It consists of a network of fine capillaries (blood vessels) and supplies the retina.
- Hypoplasia results in malformations of the blood vessels (e.g. strongly twisted) and thus in disorders of the retina.
Breeds affected
Collie, Border Collie, Australian Shepherd and Shetland Sheepdog
The mutation was also discovered in the Nova Scotia Duck Tolling Retriever in 2018.
Test Information
This mutation test detects a deletion of 7.8kb in the NHEJ1 gene.
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This test is carried out by a partner laboratory.
Genotype and Lab Report
Inheritance: autosomal recessive
→ The disease only occurs when both alleles of the gene are affected by the mutation (cea/cea). Dogs that have only one allele with the causative mutation (N/cea) are clinically healthy carriers.
Genotypes:
N/N = genetically normal
The dog has no variants for CEA and thus cannot pass it on to offspring.
N/cea = a carrier
The dog is a clinically healthy carrier. The variation is passed on 50% to the offspring, which are also carriers.
cea/cea = affected
The variation will be passed on to 100% to the offspring.
Recommendations
- Carrier animals can be bred to normal animals (N/cea x N/N). Before using the offspring in breeding, it should be tested whether they are normal or carriers.
- Mating two carrier animals (N/cea x N/cea) should be avoided because there is a 25% chance that the offspring will be affected.
- Affected animals (cea/cea) should be excluded from breeding.
Literature
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.
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 21:144-150, 2018. Pubmed reference: 28702949. DOI: 10.1111/vop.12488
Further information is available at: Online Mendelian Inheritance in Animals.