Description: CNS atrophy and cerebellar ataxia, abbreviated CACA, are a disease identified and described in the Belgian Shepherd breed. Atrophy affects all layers of the cerebral cortex with depletion of Purkinje and granular cells. Neuroaxonal degeneration affects the midbrain, brain stem, and spinal cord. Furthermore, there is a significant reduction in the amount of myelin in the white matter of the brain and spinal cord. Clinical signs include tremor with targeted movement, general increased muscle tone, decreased swallowing reflex, and brief episodic spastic attacks of varying intensity. Similar symptoms occur with mutations in other genes (SDCA1 and SDCA2). The first apparent symptoms were observed on days 12-14 after birth and gradually developed. Affected puppies have a lower body weight by an average of 10-40% compared to unaffected siblings.

CACA disease causal mutation is a homozygous ~17 kb deletion in the SELENOP gene. This deletion includes the entire protein-coding sequence of SELENOP and results in the complete absence of encoded selenoprotein P required for selenium transport into the CNS. The total levels of selenium in the blood of homozygous mutant puppies of the examined litter were reduced to approximately 30% of the value of the homozygous litter of healthy individuals. The results of the study show that deletion of the SELENOP gene in dogs causes a defect in selenium transport associated with CNS atrophy and cerebellar ataxia (CACA) (Christen M. et al. 2021).

Inheritance: autosomal recessive

Mutation: ~17 kb deletion in SELENOP gene, Chr4:66,946,539_66,963,863del17,325

Sample: EDTA whole blood (1.0 ml) or 2 buccal brushes

The analysis is suitable for the following breeds: Belgian Shepherd

Notes: Diseases with similar symptoms may be caused by mutations in the SDCA1 and SDCA2 genes.