Neuronal ceroid lipofuscinosis 6 (NCL6) is an early-onset lysosomal storage disease caused by biallelic variants in the CLN6 gene. In the Australian Shepherd it produces progressive visual deficit leading to blindness, together with cognitive and motor degeneration. It is inherited in an autosomal recessive manner and a genetic test is available.

Described in the Australian Shepherd. The literature reports only two confirmed affected dogs, so the prevalence is considered very low. There is no documentary support for extending it to the Miniature American Shepherd; any mention of that breed comes from commercial providers due to proximity of genetic background, not from published studies.

- Progressive visual deficit leading to blindness
- Anxiety and cognitive degeneration
- Ataxia, disorientation and circling
- Incoordination
- Progressive course with early onset

The causal variant of NCL6 in the Australian Shepherd was identified in 2011: a c.829T>C transition in exon 7 of CLN6 causing p.(W277R) (Katz et al. 2011). In the original study only two affected dogs were identified, so the disease appears very rare in the breed.

- Test breeding animals before breeding
- Do not mate two carriers: 25 % of the litter would be homozygous affected
- A carrier can be mated with a clear dog, testing the offspring intended for breeding
- Do not breed from affected dogs

Differential diagnosis with other canine NCLs caused by different genes (for example CTSD/NCL10, ARSG, PPT1, TPP1). The c.829T>C variant is specific to CLN6 and should not be extrapolated to other NCLs. Carriers are asymptomatic.

1. Katz ML et al. 2011. A missense mutation in canine CLN6 in an Australian shepherd with neuronal ceroid lipofuscinosis. Journal of Biomedicine and Biotechnology. PMID: 21234413
2. OMIA:001443-9615. Neuronal ceroid lipofuscinosis, 6. Online Mendelian Inheritance in Animals.