Neuronal ceroid lipofuscinosis type 8 (NCL8) in Salukis

Neuronal ceroid lipofuscinosis is a group of heterogenic inherited neurodegenerative disorders that occur in many kinds of mammals, incl. dogs, cats and humans. In some animals, the causal mutation leading to NCL has not been described yet.  In connection with NCL in animals and humans, mutations have been identified in six different genes CLNs 1,2,3,4,5,6,8. (Daly et al. 1998, Gupta et al. 2001). Each mutation of the given gene results in a unique form of NCL.

NCL occurs in several dog breeds, e.g. Border Collies, English setter, American Bull Dog, Dachshund, Polish Lowland Sheepdog or Tibetan terrier. In Saluki breed, a specific causal mutation has been indentified in connection with NCL:  the insertion c.349dupT in exon 2.  This mutation results in premature stop-codon  (p.Glu117) causing aggregation of autofluorescent storage material in the neurons  of several brain regions and also in the retina.  The neuronal ceroid lipofuscinosis is characteristic by aggregation of lipopigments (ceroid and lipofuscin) in lysosomes.

The disease is characterized by progressive neurological symptoms, including disorientation, anxiety, seizures and food intake difficulty. It usually comes to loss of vision as well.  The onset of the symptoms and clinical course of the disease are very variable and individual.  The degree of neurodegeneration increases with age. All affected individuals show psychological abnormalities and muscle spasms. There have been also observed changes in gait pattern – stumbling gait, limb stiffness.

NCL8 is inherited as an autosomal recessive trait. That means the disease affects dogs with P/P (positive / positive) genotype only. The dogs with P/N (positive /negative) genotype are clinically without any symptom. They are genetically considered carriers of the disease (heterozygotes). In offspring of two heterozygous animals following genotype distribution can be expected: 25 % N/N (healthy non-carriers), 25 % P/P (affected), and 50 % N/P (healthy carriers). Because of high risk of producing affected offspring, mating of two N/P animals (carriers) can not be recommended.

.

Publication:
Lingaas, F., Guttersrud, O.A., Arnet, E., Espenes, A.: Neuronal ceroid lipofuscinosis in Salukis is caused by a single base pair insertion in CLN8. Anim Genet 49:52-58, 2018. Pubmed reference: 29446145. DOI: 10.1111/age.12629