MRD Research and Curly Coat Syndrome
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Report of the Eye Sub-Committee - AGM 2006

ICHTHYOSIS KERATOCONJUNCTIVITIS SICCA (Dry eye/curly coat)


There have been 21 separate cases of the condition submitted to the AHT since the research started. This does not take into account the many undiagnosed cases that went unreported due to lack of knowledge. It is now believed that there were in the order of some 39 or more cases that the Michigan State University and the University of Tennessee were aware of. Several cases have occurred in Australia, Sweden and the Czech Republic. Iceland has one of the smallest gene pools and has been unlucky enough to have imported several carriers, to the point that in the period 2002-2003 there were instances of more than 50% of many litters being born affected. It seems to imply that the condition is more widespread that first though as more people come to recognise the symptoms.

Several theories have been suggested, but the most practical seems to be that the condition is inherited, probably by as simple autosomal recessive gene. This means that a percentage of the Cavalier population may be carriers and when two carriers come together and affected puppy could be seen. One would expect this to be in the ratio of one affected, two carriers and one clear. However, there have been numerous cases were half or nearly all of one litter have been affected. It is not yet known whether this is just co-incidence or some other form of inheritance at work. What has been established however is that in an affected puppy's pedigree, a suspected carrier is always identified on both the sire and dam's lines. It would seem that an affected puppy is more likely to be seen where line or inbreeding on carrier lines is carried out.

There is now sufficient pedigree data available and a genetic programme is being carried out by Dr Kathryn Mellersh, a well respected geneticist at the AHT. Twenty seven (27) candidate genes have been identified and the tests are currently in progress and final results are pending.

With written support from the CKCS Club an application was made the Kennel Club for a grant to help with the research into this condition. I am pleased to report that a grant of 4,200 has been approved by the Charitable Trust and payment has been made to the AHT.

This condition is not as widespread as some other health issues but is particularly nasty in its expression. There is no treatment for the condition, only symptom and pain relief management. It is considered by the researches to be a condition best dealt with by euthanasia as soon as it is recognised. I urge all breeders to make themselves familiar with the condition to prevent unnecessary suffering to afflicted puppies.

MULTIFOCAL RETINAL DYSPLASIA (MRD)

At the 2006 Championship show, 74 Cavaliers were examined by Mr Ian Mason; very encouragingly only one case of MRD was identified. Whether this is affected by breeders obtaining litter screening results and only offering "passes" for inspection is unknown, but over the last few years there seems to be evidence of decreasing level of ocular disease. This is very satisfactory for the breed and is a fair reflection of the efforts made by conscientious breeders to avoid producing abnormalities.

Dr Keith Barnett is continuing his research at the AHT into MRD. He suspects that the gene responsible for MRD in Golden Retrievers could be the sane as the one in Cavaliers. The AHT has received a substantial grant from the Kennel Club for research in canine ocular disease and have been successful in 2005 in identifying several genes responsible for hereditary ocular disorders in other breeds. To date they believe that they have identified the chromosome responsible for MRD but are still searching for the gene. Interestingly Leeds University is researching Genetical Retinal Degeneration in humans and it is believed to be the same gene responsible for congenital cataracts in Cavaliers and Miniature Schnauzers.

DNA was sourced from and expended parti-colour family and also a whole-colour family last year. This consisted of MRD affected Cavaliers, the parents and siblings, however Dr Barnett still needs more DNA. Ideally from 4-6 affected Cavaliers and their immediate family, if anyone can help please contact Dr Keith Barnett at the AHT.


Peter Towse
Eye Sub Committee

 
 
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