For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.
At risk dogs are highly likely to show signs of this disease in their lifetime.
Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.
The onset of clinical signs is usually by 9 months of age. NCL type 1 is a progressive condition characterized by rapidly progressing vision impairment, ataxia (uncontrolled movements), and behavioral changes, such as anxiety, sound sensitivity, and inability to recognize familiar individuals. Clinical signs of NCL1 also include general weakness and uncontrolled rhythmic head movements.
Treatment is supportive care, however, due to the progressive nature of the condition, clinical signs typically lead to euthanasia on welfare grounds.
There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.
This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to occur. A carrier dog with one copy of the NCL1 mutation can be safely bred with a clear dog with no copies of the NCL1 mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the NCL1 mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the NCL1 mutation could develop due to a different genetic or clinical cause.
All coordinates reference CanFam3.1
Sanders, D. N., Zeng, R., Wenger, D. A., Johnson, G. S., Johnson, G. C., Decker, J. E., … O’Brien, D. P. (2013). GM2 gangliosidosis associated with a HEXA missense mutation in Japanese Chin dogs: A potential model for Tay Sachs disease. Molecular Genetics and Metabolism, 108(1), 70–75. View the article