Lafora Disease

Other Names: Lafora's Disease, Myoclonus Epilepsy of Lafora, Progressive Myoclonus Epilepsy, PME
Affected Genes: NLHRC1
Inheritance: Autosomal Recessive
Mutation: chr35:16921548-16921571 (canFam3): Variable 12-mer (GCGGGGGGCGGC) repeat expansion - wild type is 1-2 copies, disease is 14-26 copies
Breed(s): Basset Hound, Beagle, Brussels Griffon, Chihuahua, French Bulldog, Miniature Wirehaired Dachshund, Newfoundland, Newfypoo, Pembroke Welsh Corgi
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Common Symptoms

Lafora disease is an inherited neurological disease affecting dogs. Affected dogs typically present after 5 years of age with progressive, partial to generalized seizures due to an abnormal accumulation of large carbohydrate molecules in the brain. As the disease progresses, affected dogs may display other clinical signs including vision loss, deafness, Dementia, myoclonus (involuntary muscle jerks), aggression, tremors, “flybiting” behavior (attempting to catch nonexistent flies), jaw smacking, urinary and fecal incontinence, loss of house training, and/or abnormal gait. Excitement or nervousness, exposure to flickering lights, sudden sounds or movements may trigger seizure activity in some affected dogs. Seizures associated with Lafora epilepsy have mixed response to treatment, becoming less effective as the disease progresses. Affected dogs are typically euthanized by 10-12 years of age due to decline in quality of life.

Testing Tips

Genetic testing of the NHLRC1 gene will reliably determine whether a dog is a genetic Carrier of Lafora Disease. Lafora Disease 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 NHLRC1 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. Dogs 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

  • Ahonen S, Seath I, Rusbridge C, Holt S, Key G, Wang T, Wang P, Minassian BA. Correction to: Nationwide genetic testing towards eliminating Lafora disease from Miniature Wirehaired Dachshunds in the United Kingdom. Canine Med Genet. 2021 Dec 27;8(1):14. Erratum for: Canine Genet Epidemiol. 2018 Mar 27; 5:2. [PubMed: 34961559]
  • Lohi H, Young EJ, Fitzmaurice SN, Rusbridge C, Chan EM, Vervoort M, Turnbull J, Zhao X, Ianzano L, Paterson AD, Sutter NB, Ostrander EA, Andre C, Shelton D, Ackerley CA, Scherer SW, Minassian BA. Expanded Repeat in Canine Epilepsy. Science. 2005 Jan 7;307(5706):81. [PubMed: 15637270]
  • Sainsbury R. DNA screening for Lafora’s disease in miniature wire-haired dachshunds. Vet Rec. 2014 Dec 6;175(22):568. doi: 10.1136/vr.g7417. [PubMed: 25480901]
  • Swain L, Key G, Tauro A, Ahonen S, Wang P, Ackerley C, Minassian BA, Rusbridge C. Lafora disease in miniature Wirehaired Dachshunds. PLoS One. 2017 Aug 2;12(8):e0182024. doi: 10.1371/journal.pone.0182024. [PubMed: 28767715]
  • von Klopmann T, Ahonen S, Espadas-Santiuste I, Matiasek K, Sanchez-Masian D, Rupp S, Vandenberghe H, Rose J, Wang T, Wang P, Minassian BA, Rusbridge C. Canine Lafora Disease: An Unstable Repeat Expansion Disorder. Life (Basel). 2021 Jul 14;11(7):689. [PubMed: 34357061]
  • Webb AA, McMillan C, Cullen CL, Boston SE, Turnbull J, Minassian BA. Lafora disease as a cause of visually exacerbated myoclonic attacks in a dog. Can Vet J. 2009 Sep;50(9):963-7. [PubMed: 19949558]