An explanation on MHC haplotypes
Having recently spoken on a facebook group and finding myself explaining MHC haplotypes, I realised how very few people understood their function.
I sent a certain Canadian breeder a copy of the notes for my original seminar concerning MHC a couple of years ago, but from her reply to this group it was apparent she had no understanding at all of what I had written to her at that time. I therefore realised this was probably the same for many and decided to write it in much more simple terms! . Remembering the words of Einstein who said that if a subject could not be explained in simple terms it had never been understood in the first place..I would also like to add, the idea of simplifying this complex subject by comparing this group of genes to a medical bag was the brain child of my husband Keith, born during a long conversation on this subject when I was planning my first seminar for EACA almost 3 years ago. It was perfect. I would also like to say that everything I have written is based upon my own interpretation and understanding of this complex subject. My husband Keith is a chemist, and my youngest son was (at the time I wrote my first seminar) studying Biology at Oxford. The two of them became my sounding boards. My original research was done via the internet and through the spoken word and one of the articles I found most interesting during this research can be found via a link on my page 'Breeding for a future' and anyone wishing to learn more on this subject may wish to read this information, I know others have copied the information on this same link and added it to their health pages without paying due credit. However, I always provided a link to the original out of respect for the true author. I will be giving another seminar covering Haplotypes and other associated information, so if you are interested...watch for details! Anyone can copy and paste or quote from a book, some can rearrange the words of others but still have no understanding, a true teacher must be able to do the research and then prove their understanding by making things simple, I hope I am able to do this and in so doing, help others to understand the importance of this subject.
So if you hear someone explaining MHC using the 'medical bag' terminology...you know these words were successfully repeated, and Keith's 'brain child' is growing to adulthood...lol!
Well I think it is time to explain MHC haplotypes in a simple way rather than by adding links to the work of others on this subject. It is a subject very obviously not understood by the vast majority and so I hope to help in this matter. Haplotypes are a unit or collection of genes, they are inherited as a group rather than in a single fashion as is normally the case. We didn't really know or understand MHC haplotypes until very recently, so it is hardly surprising to discover that Breeders know very little about them, or that the subject is not covered in our best loved books on the breed. MHC are the group of genes that protect the immune system, they are dogs first line of defence against disease. Because of the way that bacteria works and evolves, these genes have a higher level of mutation than other genes, they need to be able to mutate quickly in order to protect the dog against a multitude of ever evolving bacteria and others such things. I am trying to make this really simple as I know that English is not the mother tongue of every one reading. It is also a complex subject. We could think of MHC haplotypes as a medical bag, filled with an arsenal of 'goodies' that will help the dog to fight infection and develop a strong and healthy immune system. In the Canine world, there are hundreds of sets of MHC that ensure the dog population remains strong and healthy, however, when we begin line breeding we drastically reduce variety in this essential area, this weakens the immune system. We need a wide variety of MHC to enable us to ward of new types of infection. Line breeding is not common in every breed of dog, in fact in one study in the UK Greyhounds were found to have 0% inbreeding (this means NO line-breeding) not only can they still be identified as Greyhounds...but they have consistently been placed in groups in the UK which is more than can be said for the Rough Collie, a breed in which line breeding has always been fashionable. There is a study of MHC at the moment in England, and I believe there is also one in America. In answer to a Canadian breeder, YES there is a DNA test that can establish MHC and the study I am referring too is establishing the amount of individual MHC haplotypes within each individual breed. In Breeds such as the Greyhound, the amount of such Haplotypes is high creating a diverse and healthy gene pool. Unfortunately, in breeds such as the Rough Collie, where fashion has dictated a long history of line breeding, MHC is thought to have been reduced to only 1-3 sets across the entire UK population! I believe they are discovering a similar state of affairs in the American Rough Collie gene pool. However, the 3 possible sets of different Haplotypes found in the UK gene pool will have mutated differently to the 3 possible sets found in American collies. I hope you are all still with me, If not please feel free to ask me questions. So where is this taking us? when we line breed we condense the genes of one or two individuals, and this does not only affect the outward appearance. Unfortunately it also reduces the available sets of Haplotypes, so in effect we are inadvertently breeding to reduce the ability of our Dogs to cope with disease. This is the reason that during the last 30 years there has been a steady increase in auto immune related problems. If a huge virus entered the gene pool, it is possible that the vast majority of our Collies would die, because with a severe loss of diversity in this area, our dogs would not have the wide and varied MHC necessary for the larger part of the breed to survive. Armed with this knowledge, I have to ask myself a question. Is it ethical to continue with a program of close line breeding? Am I really wishing to bring innocent and trusting puppies into the world, knowing I am purposely reducing their chances of survival? If we are prepared to combine the few American type sets of MHC with the few available sets of MHC here in the UK, we are creating the possibility of having twice the number of available of MHC. If we can consciously keep the gene pools well mixed, the shuffling around of these Haplotypes will create stronger immune systems, providing these hard working genes with a chance to mutate as they should. Interestingly, type has remained 'fixed' within the Smooth collie population despite them being numerically small in Europe. Despite the fact that Smooth collies are numerically low, the Inbreeding coefficient is much lower than that of the Rough Collie..!!! this means there is less line breeding...and yet they have retained type throughout their history whilst the Roughs in the UK have lost type. I think I know why this is so. Smooth Collie breeders have set 'the Breed standard' as the type to aim for, rather than the fads and fashions of individual kennels. They are using the standard as their goal in order to set type and this creates unity within the breed as a whole. They have worked together out of genuine love for the Breed. On the other hand, Rough Collies breeders have segregated themselves by working to produce individual 'kennel type'. The first way is born of love, and the second is born of Ego. If we mix American and English Collies, it is true that we shall possibly change type, although I think we shall improve it in the majority of instances, but more importantly, we shall be breeding much healthier puppies out of love rather than Ego.
Out of interest I checked out the inbreeding coefficient of several breeds on the Kennel Clubs 'Mate select' program. The vast majority of pedigree dogs actually have an average inbreeding coefficient below that of the Rough Collie. In fact most breeds of pedigree dog are not nearly so inbred as some would have us believe!!!
SHETLAND SHEEPDOG 5.8%
SMOOTH COLLIE 5.8%
AUSTRALIAN SHEPHERD 2.4%
BORDER COLLIE 3.4%
ROUGH COLLIE 13.7%