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Gordon setter pup

DNA Testing and Autosomal Recessive Genes

Certain inherited conditions are caused by autosomal recessive genes that are faulty and this means that puppies need to inherit one copy of the faulty gene from each parent to develop the condition; both dog and bitch puppies can be affected.

If it has no copies of the faulty gene it is clear and can never develop the disease nor pass on a defective gene. If it only receives one copy it will be a carrier and will never develop the disease, but will pass on the gene to about 50% its offspring. The difficulties arise firstly in identifying those dogs that are carriers, because if you mate carrier to carrier, bearing in mind they show no signs of the disease or of being a carrier, then about 25% of the offspring will be affected, about 50% will be carriers and about 25% will be clear. Without a DNA test carriers can only be identified if they produce affected puppies and only then if mated to another carrier and by then, particularly if the disease is one that has a late onset, many puppies could be carriers waiting to be mated to other carriers. The second difficulty is identifying affected stock if the condition does not occur until the dog is relatively old.

With a DNA test breeders know for certain whether a dog is affected, carrier or clear and that will help them make informed decisions. Breed Clubs, in conjunction with KC, are able to formulate a control scheme that is individually tailored to their breed.

Each DNA test is specific to a particular mutation and will not establish whether or not a puppy will develop another condition.

CLEAR: has two normal genes so will never develop the specific condition for which the test is designed. It can only pass on a normal gene to its offspring.

CARRIER: has one faulty gene and one normal gene and will never develop the condition for which the test is designed but will pass on either a normal or faulty gene to its offspring: approximately half of its progeny will inherit the mutant gene.

AFFECTED: has two copies of the faulty gene and will develop the condition for which the test is designed. It can only pass on the faulty gene to its offspring.

By establishing the genetic status of a dog and bitch before mating it is possible to predict the probability of the clear, carrier or affected pups in that mating.

Any mating that produces an affected pup should be avoided so there should be no matings of carrier to carrier, carrier to affected or affected to affected. By avoiding these combinations then no more puppies affected with the condition for which the test is designed need be born.

Clear to clear is the ideal mating as it will not produce affecteds or carriers but this may not be possible immediately after a test becomes available as it will depend on the number of carriers within the breed.

However, always providing one parent is clear, other combinations can be used that do not produce affecteds. Clear to carrier will produce a combination of clears and carriers and the puppies will need to be tested if they are going to be used for breeding. Clear to affected will produce all carriers and this combination is best avoided. By careful selection of parents and only using a carrier with other desirable characteristics and of particular merit to the breed it is possible to retain breed characteristics and, over the generations, breed out carriers. If there are many carriers in a breed then it would be inadvisable to discount them as the subsequent breeding pool could be greatly diminished.

It is important to realise, with the exception of affected to affected, clear to clear and also affected to clear the percentages are only statistical and will vary from litter to litter.

In Irish Setters we have 2 established DNA tests and one very recently available.

Both the PRA rcd1 and CLAD tests have been used effectively and it appears that both conditions have been eradicated from the breed in Kennel Club registered stock in the UK. The latest test for PRA rcd4 has very recently been made available to breeders and there is no reason why the same success should not be had with this latest test.

This article has been reviewed by Professor Jeff Sampson the Kennel Club's Canine Geneticist, now retired.

Updated: Saturday, November 15, 2014 - 10:01

Epilepsy Research at Helsinki University

Hannes Lohi and his team at Helsinki University are carrying out research into epilepsy in Irish Setters. Below is a statement from Lotta Koskinen who is involved:

Right now we are gathering more samples from Irish Red Setters with idiopathic epilepsy and for the research we are also gathering samples from over 7 year old healthy dogs and dogs with epilepsy in the close family. Adjoining the samples, we also gather general health information with a form and illness descriptions from the dogs with idiopathic epilepsy with a separate epilepsy questionnaire.

Instructions

for taking the sample and sending it to us can be found at:

www.koirangeenit.fi/in-english/participate/

The epilepsy questionnaire can be found here in several different languages:

www.koirangeenit.fi/osallistuminen/lomakkeet/

At the moment we have samples from 134 Irish Red Setters in our data base and six out of these have epilepsy. We have seven samples from Irish Red and White Setters. We have however done preliminary research in identifying epilepsy genes with samples from our partner in the United States of America. That research consisted of 75 dogs (40 with epilepsy and 35 comparison dogs). This also included samples from six Finnish dogs. With this set of samples we couldn’t find genes predisposing to epilepsy and we are now continuing our research by collecting new samples.

The Dutch Irish Setter Club has been in contact with us earlier and we have agreed on a sample collection with them. Our partner veterinarians from the University of Utrecht are coordinating the local sample collection. Samples from other countries can be sent directly to us.

Unfortunately I cannot say for certainty how many samples we need in this breed to find the genes causing epilepsy. On top of the actual amount of samples many other things have an influence, such as how “unified” the genetic background for epilepsy is in this breed. If the genes don’t play a major part or there are several genes behind the illness we need a lot more samples than if there was only one gene determining a majority of the illness. If the epilepsy symptoms are very mild or seizures are rare, it might be difficult for the owner to recognise the illness and thus there could be affected dogs among the healthy comparison group. That is another reason why the sample amount should be as high as possible so these aberrations wouldn’t play such an important role in the results.

Finding the gene is a sum of many things, e.g. the amount of samples, the amount of predisposing factors for epilepsy in the breed and the accuracy and reliability of the information related to the dogs in the research. Our goal could be to gather up samples from 80 to 100 dogs with idiopathic epilepsy and continue the research with this material.

Best regards Lotta Koskinen

She writes further :

We are collecting samples from dogs with epilepsy, and from healthy old (age >7 years) dogs. Also samples of relatives of dogs with epilepsy can be useful, especially if the relatives also have epilepsy. Along with samples, we also collect detailed health information and pedigree information from each dog. We have a "sample form" we would like to be filled on each sampled dog, and for dogs with epilepsy we also have a 10-page epilepsy questionnaire . Both forms (sample form and epilepsy questionnaire) can be downloaded here:

www.koirangeenit.fi/in-english/participate/

Because taking blood samples for research purposes is not possible in the UK, we could take buccal swab samples instead.

Swab kits are now available for this research and include:

Two questionnaires which they ask you to complete. More copies of either can be downloaded from the link above.

A leaflet giving sample taking instructions for the DNA test. It is important that there is no contamination from other dogs and extra care needs to be taken if you have more than one dog at home. If providing more than one sample please make sure each one is labelled correctly and is for the right dog. Please take the samples as carefully as possible and according to the instructions. This is important, because there can be a lot of variation in the DNA yield depending on how the samples are taken. They have noticed now that they have started with the DNA extractions that the DNA yield has often been quite low. Taking buccal swab samples is not always easy, because it is really important to brush the buccal surface several (around 20) times on both sides of the dog's mouth. This is the only way to get enough DNA for large-scale genetic studies.

A letter giving permission for the samples to be sent from one EU country to another and one for our Royal Mail which you must sign.

Please make sure that you enclose your dogs’ pedigree as well. This information will not be divulged by the University. Results will be released only with your consent.

Please note that although the sample form mentions blood samples we are submitting buccal swabs. It may take longer than the 2 – 3 days mentioned to get to the University from UK so either sending the swab on a Monday may be best or at the end of the week so it doesn’t arrive at the weekend. Please consider sending it by express mail.

If you would like a pack or further information please contact either:

Lynne Dale: hartsfell

talktalk [dot] net or Meg Webb: megwebb1

aol [dot] com

All packs are provided free of charge and your only cost is sending the swabs to Finland.

This initiative is supported by the Joint Irish Setter Breed Clubs' Committee.

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