Dwarfism Gene Types

[EMB]

John thank you so very much for your efforts here in answering our questions as well as in the research you are undertaking.

You mentioned in an earlier post on the main forum that there is more than one dwarf gene type. I know that dwarfism manifests itself in more than one way but I am thinking that is not what you are referring to. Or is it? Are you thinking that a given gene will always produce a minimal dwarf and so on?

If the gene types you are referring to are in fact indicators of something other than dwarf types, what is your research suggesting the significance of that might be for owners/breeders? Given what you know today, does that alter what we need to be looking at/for in our own animals and when purchasing new stock?

Thank you again!

Eileen

 

[Arion Mgmt]

Your question is a little confusing but I will try to answer it.

"You mentioned in an earlier post on the main forum that there is more than one dwarf gene type. I know that dwarfism manifests itself in more than one way but I am thinking that is not what you are referring to. Or is it? Are you thinking that a given gene will always produce a minimal dwarf and so on? "

Each dwarf type, if they are definite different types will most likely involve different genes for each type. This means type 1 is caused by a mutation in gene A for example, and type 2 is caused by a mutation in gene D, and so on. So there is not a single dwarf gene for all the types and the gene is then changed differently to cause the different types, that most highly unlikely to be happening. This is given that in other animals similar dwarfisms to what I see in the Miniatures are occuring and they involve different genes respectively.

First there really is no "minimal dwarf" that has become a slang term for carriers that show alot of characteristics of dwarfism, and for dwarfs that are very "good". If you dont know if the horse is a carrier, are you sure it is just not bad conformation, again some people can be quite wrong sometimes, and most of the time they can be right. This is all subjective right now.

There are normal horses with a recessive gene that might show some expressivity, as I explained in another thread, by Annette. The horse carrying that recessive gene is normal, in a sense. And a dwarf that is a "good" dwarf is not any less of a dwarf than a more severely affected dwarf of the same type, they are both homozygous for the dwarf gene. Again the expressivity manifested itself differently in each one, same as seen in humans.

"If the gene types you are referring to are in fact indicators of something other than dwarf types, what is your research suggesting the significance of that might be for owners/breeders? Given what you know today, does that alter what we need to be looking at/for in our own animals and when purchasing new stock?"

That question doesnt apply I think with what I wrote above. There are probably 4 different types of dwarfism probably caused by 4 different genes that have been altered from normal somehow. There is a possibilty that some of these dwarfisms , I think maybe type 3, might be a combination of two mutated genes that cause a type of dwarfism. Again this is all circumstantial to my findings.

The significance of my findings for breeders is that we will be able to improve this breed very quickly if the diseased genes are found and tests can be made. I do not believe carriers should be totally eliminated if that is what yo are asking. I believe we should look at what other very smart horse breeds did with diseases within a large population of a breed, i.e. HYPP in the Quarter horse.

John