Neonatal cerebellar cortical degeneration in Hungarian Vizsla

Neonatal cerebellar cortical degeneration (NCCD) or cerebellar  abiotrophy is a neurodegenerative disease that affects several canine breeds, however the mode of inheritance has only been clarified in Hungarian Vizslas.  The characteristic feature of this inherited disease is cerebellar ataxia. The onset and the progression of the disease differ among the various breeds.

The typical ataxia begins to develop at around three months of age and the progression is relatively fast. The affected dogs suffer from general lack of coordination, intention tremor and head tremor, insufficient response to threat and symptoms of dysfunction of balance organ incl. nystagmus.

NCCD is caused by mutation c.2653+1G>A in SNX14-gene that takes part in maintenance of normal neuronal excitability and synaptic transmission. The primary effects of the mutation are degeneration and loss of Purkinje cerebellar cells and the secondary effects include degeneration of cells of the granular and molecular cell layers that results in general cerebellar atrophy.

NCCD is a recessively inherited disease. The disease develops in dogs which inherit the mutated gene from each parent.  These dogs are designated as P/P (positive/positive). The carriers of the mutated gene are designated as N/P (negative/positive). The carriers inherited the mutated gene from one parent only and are without clinical signs. However, they pass the disease on to their offspring.  When mating two heterozygotes (N/P), there will be theoretically 25% of the offspring healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will be affected by NCCD.  Mating one healthy dog (N/N) with a carrier of this mutation (N/P) will theoretically produce 50% carriers and 50% healthy offspring.  If a carrier (N/P) is mated with an affected dog (P/P), there will be theoretically 50% affected dogs and 50% carriers.

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References:

Joe Fenn, Mike Boursnell, Rebekkah J. Hitti, Christopher A. Jenkins, Rebecca L. Terry, Simon L. Priestnall, Patrick J. Kenny, Cathryn S. Mellersh and Oliver P. Forman: 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 (2016)