Neonatal Cortical Cerebellar Degeneration (NCCD)
Neonatal cortical cerebellar degeneration (NCCD) is also known as cerebellar abiotrophy and it is an inherited disorder described in several dog breeds including the Beagle dog breed. It is a part of group of inherited neurological degenerative diseases, which are found in several mammalian species, including humans, horses and dogs.
The cerebellum is also known as the ”little brain”. It is a region of the brain important for motor control and coordination. Cerebellar damage results in disorders in fine movement, equilibrium, posture and motor learning.
Characteristics and Symptoms
Neonatal cortical cerebellar degeneration (NCCD) is characterized by progressive degeneration of neurons localized in the cerebellar cortex. Clinical symptoms are cerebellar dysfunction, which are ataxia-dysmetria, broad based stance, loss of balance and intentional tremors. Affected Beagles show wide based-stance, loss of balance, with tendency to lean or fall towards both sides, and dysmetric gait with inability to regulate rate and range of movement. Histopathological examinations reveal extensive degeneration to complete loss of Purkinje cells and secondary lesions in the molecular and granular layers. Where Purkinje cells loss was noticed, increased number of astrocytes was identified. Normal cerebellum has a weight of 10-12% of the brain, while in affected Beagles it was measured cerebellum’s weight of 5% of the brain. Age of neonatal cortical cerebellar degeneration (NCCD) onset in affected beagles is around 3 weeks of age. With slow progression of the disorder, and inability of puppy’s recovery, affected dogs are often euthanized.
Neonatal cortical cerebellar degeneration (NCCD) is associated with a mutation in the SPTBN2 gene. The disorder is inherited in an autosomal recessive manner. Healthy parents of an affected dog are obligate heterozygotes, and therefore carry one mutant allele. Heterozygotes have 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.
Forman OP, De Risio L, Stewart J, Mellersh CS, Beltran E. Genome-wide mRNA sequencing of a single canine cerebellar cortical degeneration case leads to the identification of a disease associated SPTBN2 mutation. BMC Genet. 2012 Jul 10; 13:55.