Breeds Affected: Dachshund
Samples Accepted: Blood, Buccal Swabs
Disease Information: NCL2 is a lysosomal storage disease with an onset of symptoms when affected pups are 6-7 months of age. Retinal changes lead to a progressive vision loss, beginning with difficulty see in dim light. Difficulty with balancing and walking, tremors, muscle twitching, seizures and other physical problems develop in parallel with behaviour changes such as hyperactivity, aggression, and a decline cognitive abilities. Affected dogs usually die by 12 months of age.
Inheritance Information: NCL2 is autosomal recessive, meaning that animals with two copies of this allele will be affected. Animals with one copy of the gene will be clinically-normal carriers.
The possible genotypes are:
N/N The dog is normal, and cannot produce affected offspring.
N/ncl2 The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/nlc2 carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
ncl2/ncl2 The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/nlc2 carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/ncl2 x N/N) without any risk of producing affected offspring. The offspring should be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/ncl2 x N/ncl2) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (ncl2/ncl2) should not be used for breeding.
Test Information: This mutation test identifies a single base deletion in exon 4 of the TPP1 gene.
Awano, T., Katz, ML., O’Brien, DP., Sohar, I., Lobel, P., Coates, JR., Khan, S., Johnson, GC., Giger, U., Johnson, GS.: A frame shift mutation in canine TPP1 (the ortholog of human CLN2) in a juvenile Dachshund with neuronal ceroid lipofuscinosis. Mol Genet Metab 89:254-60, 2006. Pubmed reference: 16621647. Doi: 10.1016/j.ymgme.2006.02.016.
Further information is available at the Online Mendelian Inheritance in Animals website.