Deutsch
Hrvatski
Русский
Português
Congenital Eye Malformations (CEM) - Golden Retriever
| Acronym: | CEM |
| Gene: | SIX6 |
| Mutation: | c.487C>T |
| Inheritance: | Autosomal Incompletely Dominant |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Congenital Eye Malformations (CEM) is a heterogeneous group of genetic eye disorders with more than 30 variants reported in dogs. CEMs affect different dog breeds including Golden Retrievers and are characterized by disturbance of dark vision, visual field defects, and retinal abnormalities which can progress to blindness. Affected dogs usually have unilateral or bilateral retina dysplasia and/or optic nerve hypoplasia. Eye malformations in Golden Retrievers are caused by a novely discovered mutation in the SIX6 gene. This gene is found in a cluster of related genes on chromosome 14 and encodes a protein that is a homeobox transcription factor with a known role in eye development.
Eye malformations in Golden Retriever dogs are inherited as an autosomal dominant trait with incomplete penetrance meaning not only dogs with two mutated genes can develop the disease, but also dogs carrying only one mutated gene. In this case, most of the heterozygotes develop mild forms of the diseases, but there have been reported cases of heterozygous dogs that develop more severe forms causing total blindness. Early detection by genetic testing can identify affected dogs and help breeders in selecting mating pairs and preventing the future development of the disease.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
AFFECTED HETEROZYGOTE |
Tested mutation was detected in animal with „affected heterozygote“ result. Animal tested as affected heterozygote has one wild-type and one mutation allele, it is in heterozygous state. It is likely to develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
**Penetrance of tested mutation, and potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Hug, P., Anderegg, L., Dürig, N., Lepori, V., Jagannathan, V., Spiess, B., Richter, M., & Leeb, T. (2019). A SIX6 Nonsense Variant in Golden Retrievers with Congenital Eye Malformations. Genes, 10(6), 454. https://doi.org/10.3390/genes10060454