Neuronal ceroid lipofuscinosis type 6 (NCL6) in Australian Shepherds

NCLs are a group of inherited, neurodegenerative, lysosomal storage disorders occurring in many kinds of mammals inclusive dogs, cats and humans.  NCL occurs in several dog breeds, such as, for example, Border Collies, English setters, American bulldogs, and dachshunds, Polish Lowland Sheepdogs or Tibetan Terriers.   Specifically, the type NCL6 has been found in Australian Shepherds.

The cause of this disease has been identified as substitute point mutation in CLN6-gene. The NCL disorder is characterized by excessive accumulation of waste compounds (lipopigments) primarily in the cells of the nervous system. The nerve cells in the cortex and the cerebellum and the retinae cells are affected and destroyed due to the high content of lipofuscin and its increasing pressure. The affected dogs start showing signs of neurodegeneration due to NCL6-muation around a year and a half of age.

The signs may include loss of vision, behavioural changes (irrational fears and anxiety, disorientation even in familiar environment, dementia, hyperactivity or aggression), worsening of motor and cognitive abilities, seizures which may look like epileptic seizures. As the NCL cannot be cured, it ends by premature death of the affected dog, usually within one year after the first signs appear.

NCL6 is described as a very rare disease. Although this disease occurs very seldom, it should not be underestimated. Genetic tests are a reliable indicator of this disease and may help responsible breeders eliminate production of affected puppies.

NCL is inherited autosomally recessively which means that the disease develops only in those dogs who inherit mutated allele from both parents. Carriers of mutated allele (heterozygotes) are clinically healthy but transmit the mutation on their descendants. In case of mating two heterozygous dogs there is a theoretical chance that 25% of descendants will be absolutely healthy, 50% will be carriers a 25% will inherit from both parents mutated allele and therefore will be NCL affected.

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References:

Martin L. Katz, Fabiana H. Farias, Douglas N. Sanders, Rong Zeng, Shahnawaz Khan, Gary S. Johnson and Dennis P. O’Brien: A Missense Mutation in Canine CLN6 in an Australian Shepherd with Neuronal Ceroid Lipofuscinosis; Journal of Biomedicine and Biotechnology, Volume 2011, Article ID 198042, 6 pages, doi:10.1155/2011/198042