Hereditary cerebellar ataxia of juvenile to adolescent onset described in the Old English Sheepdog (Bobtail) and Gordon Setter, caused by a variant of the autophagy gene RAB24. It produces progressive cerebellar degeneration with incoordination of gait and balance. It is one of the best molecularly characterized hereditary ataxias in dogs.

Documented in Old English Sheepdog and Gordon Setter with the same variant (Agler et al. 2014). No published population frequency data.

- Ataxia of the gait of juvenile to adolescent onset
- Incoordination and dysmetria
- Balance disturbances and nystagmus
- Progression of the ataxia
- Absence of primary systemic signs

Agler et al. (2014) combined linkage analysis in Old English Sheepdogs, sequencing and genotyping to localize the locus and propose the RAB24 c.113A>C (p.Q38P) variant as causal, later confirming it in Gordon Setters.

- Test Old English Sheepdog and Gordon Setter breeding dogs before mating
- Autosomal recessive inheritance: do not use homozygotes as breeding dogs
- Do not cross two carriers (25 % homozygotes per litter)
- A carrier may be crossed with a clear individual; test the offspring intended for breeding
- Record the genetic status in the pedigree

Differential diagnosis with other degenerative and malformative ataxias (e.g. Chiari malformation, spinocerebellar degenerations). The RAB24 test is specific for this variant and does not rule out other causes of ataxia.

Agler C et al. 2014. Canine hereditary ataxia in old english sheepdogs and gordon setters is associated with a defect in the autophagy gene encoding RAB24. PLoS Genet. PMID: 24516392