Lafora's Disease

In Miniature Wire Haired Dachshunds

Lafora’s disease is an inherited, late onset, progressive myoclonic epilepsy.  This degenerative neurological disease has been identified in Miniature Wirehaired Dachshunds. The disease is characterised by myoconus. Typically this looks like a backwards shuddering/jerking of the head when there is movement towards the eyes, when light intensity increases, when there is flickering light (e.g. television) or at sudden noises. Some dogs also develop epilepsy. Middle aged to older dogs (age range 5-8 years) of both sexes can be affected. Unfortunately there is not a completely effective treatment, however many are improved on anti-epileptic drugs. 

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The abnormal gene which causes this disease has been identified and a DNA test is available (but only from a laboratory in Canada). This is especially important as the disease develops after the normal breeding age, so an early test could provide a way for breeders to “breed away” from this problem.

  

If a dog has tested positive (affected) then both parents and all the offspring of that dog are either carriers or affected.

We have had various queries about the pictorial diagram that shows how the genetic mutation is passed on. The percentages illustrated in the pictorial diagram are not absolute guarantees for each litter – they are the potential incidence over time. To explain further: Each animal has 2 copies of the gene. A Clear has 2 good genes A Carrier has one Good and one Faulty gene An Affected has 2 Faulty genes Therefore: If you mate 2 Clears – you will get all Clear progeny If you mate a Clear and a Carrier You could get all Clear, all Carrier or a mixture of each. This is because each parent contributes one of their genes to each progeny. Therefore if the Carrier passes on its Good Gene, it will join with a Good gene from the Clear parent and produce a Clear puppy.

Equally, if the Carrier passes on its Faulty gene, that will give the puppy one Good and one Faulty Gene and it will be a Carrier. You cannot get an Affected from this mating because Affecteds have two Faulty Genes and in this instance, the Clear parent can only contribute Good genes so each puppy will have at least one 

Lafora Genetics Chart

Click to Enlarge

good gene. There is no way of telling how many of each (Clear and Carrier) will be produced – that is why it is wise to test the progeny so we know where the Carriers are in the population. If you mate Two Carriers You could get Clear, Carrier or Affected puppies. This is because each parent could contribute either a Good or a Faulty gene to each puppy.

Therefore, two Faulty genes produce an Affected, one Good and one Faulty gene produces a Carrier and two Good genes produce a Clear. There is no way of telling how many of each will be produced in a litter and no guarantee if one of the litter is Clear, that the others will also be. If an Affected is used in a breeding programme, all its progeny will be at least Carriers because it has 2 faulty genes so cannot pass on a good gene. If put to a Clear, all the progeny will be Carriers. If put to a Carrier, all the progeny will be either Carrier or Affected, depending whether the Good or Faulty gene from the Carrier is replicated in each puppy. 

Any queries email: philip@dance3333.plus.com