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Cerebellar Cortical Degeneration Hungarian Vizsla Type (CCD)
| Acronym: | CCD |
| Gene: | SNX14 |
| Mutation: | c.26531G>A |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Cerebellar cortical degeneration Hungarian Vizsla Type is a hereditary disorder of the central nervous system affecting the Hungarian Vizsla breed. Degenerative cerebellar diseases are collectively known as abiotrophies and are characterized by neuronal degeneration and neuronal loss. Cerebellar abiotrophies have been diagnosed in several dog breeds, such as Beagles, Rhodesian Ridgebacks, Old English Sheepdogs, Gordon Setters, and Scottish Terriers. The disorder differs among these breeds by the angle of symptoms’ onset as well as the causative mutation. Cerebellar cortical degeneration Hungarian Vizsla Type appears to be a juvenile form of the disease.
Histopathological examination of CCD-affected dogs reveals a loss of Purkinje neurons in the cerebellar cortex. In some breeds, neurodegenerative lesions can be observed also outside the cerebellum, such as the spinal cord the cerebral cortex, and the brain stem. The first visible symptoms may include stumbling, truncal sway, and ataxia exacerbated by lifting the head up and negotiating stairs. With the disorder progression, obvious ataxia develops, characterized by dysmetria, nystagmus, coarse intention tremor, variable loss of menace reaction, and truncal sway. In the final stages of the disease, dogs become unable to walk without falling repeatedly.
Cerebellar cortical degeneration in Hungarian Vizsla Type is caused by a mutation in the SNX14 gene. The disorder is inherited in an autosomal recessive pattern. Healthy parents of an affected dog are obligate heterozygotes and therefore carry one mutant allele. Heterozygotes are carriers and show no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
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. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not 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.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Fenn, J. et al (2016) Genome sequencing reveals a splice donor site mutation in the SNX14 gene associated with a novel cerebellar cortical degeneration in the Hungarian Vizsla dog breed. BMC Genetics 17:123.