Neuronal Ceroid Lipofuscinosis 7

Other Names: Amaurotic idiocy, Batten disease, NCL, NCL7
Affected Genes: MFSD8
Inheritance: Autosomal Recessive
Mutation: chr19:13010761 (canFam3): 1 bp deletion (del T)

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Common Symptoms

Neuronal ceroid lipofuscinosis 7 (NCL7) is a lysosomal storage disease affecting Chihuahuas. Affected dogs lack a specific Enzyme necessary for normal metabolism. As a result, there is an abnormal accumulation of waste compounds in cells which affects the normal function of the brain and nervous system. Affected dogs typically present around 1 to 2 years of age with a variety of progressive neurological symptoms including behavioral and personality changes, disorientation, sensitivity to loud noises, abnormal gait, wide-based stance, vision loss, decreased reflexes, and seizures. Most affected dogs will die or be humanely euthanized by 2 to 3 years of age.

Breed-Specific Information for the Chihuahua

The Mutation of the MFSD8 gene associated with neuronal ceroid lipofuscinosis 7 has been identified in the Chihuahua, although its overall frequency in this breed is unknown.

Testing Tips

Genetic testing of the MFSD8 gene in Chihuahuas will reliably determine whether a dog is a genetic Carrier of neuronal ceroid lipofuscinosis 7. Neuronal ceroid lipofuscinosis 7 is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the MFSD8 gene mutation. Reliable genetic testing is important for determining breeding practices. Because symptoms do not appear until adulthood, genetic testing should be performed before breeding. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Chihuahuas that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.

References

  • Ashwini A, D’Angelo A, Yamato O, Giordano C, Cagnotti G, Harcourt-Brown T, Mhlanga-Mutangadura T, Guo J, Johnson GS, Katz ML. Neuronal ceroid lipofuscinosis associated with an MFSD8 mutation in Chihuahuas. Mol Genet Metab. 2016 Aug;118(4):326-32. [PubMed: 27211611]
  • Faller KME, Bras J, Sharpe SJ, Anderson GW, Darwent L, Kun-Rodrigues C, Alroy J, Penderis J, Mole SE, Gutierrez-Quintana R, Guerreiro RJ. The Chihuahua Dog: A New Animal Model for Neuronal Ceroid Lipofuscinosis CLN7 Disease? J Neurosci Res. 2016 Apr;94(4):339-47. [PubMed: 26762174]
  • Guo J, O’Brien DP, Mhlanga-Mutangadura T, Olby NJ, Taylor JF, Schnabel RD, Katz ML, Johnson GS. A rare homozygous MFSD8 single-base-pair deletion and frameshift in the whole genome sequence of a Chinese Crested dog with neuronal ceroid lipofuscinosis. BMC Vet Res. 2015 Jan 3;10:960. [PubMed: 25551667]