Late-Onset Spinocerebellar Ataxia

Ataxia is characterized by uncoordinated movements and represents a relatively nonspecific clinical sign. The late onset spinocerebellar ataxia discussed here is due to mutations in the CAPN1 gene.


Puppies that develop this type of ataxia have uncoordinated movements and balance problems that usually appear between 6 months and the first year of life. As the disease progresses, they fall more regularly and the pelvic limbs are more severely affected.

Disease Management

There is no cure for the disease. Dogs with spinocerebellar ataxia are often euthanized because of their poor quality of life.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

Thanks to the study by Forman et al. (2013) it was possible to identify the c.344G>A variant of the CAPN1 gene as a possible cause of late-onset ataxia in Parson Russell Terrier dogs. The CAPN1 gene encodes for the catalytic subunit of calpain 1, an essential protein in regulating the cell cytoskeleton and signal transduction. Calpains are proteins found in many living beings and at the level of the nervous system, it is suggested that they could have a relevant role in neuronal damage following trauma. However, their relationship in the development of pathology continues to be studied. It has recently been shown that calpain 1 may be involved in the development of nerve cells in the cerebellum and may also play a role in synaptic plasticity and learning and memory.

Most affected breeds

  • Jack Russell Terrier


Forman OP, De Risio L, Mellersh CS. Missense mutation in CAPN1 is associated with spinocerebellar ataxia in the Parson Russell Terrier dog breed. PLoS One. 2013 May 31;8(5):e64627.

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