mini charlie,
I do not know what you know about disease research whether in animals or humans but I will try to explain the difference and necessity of doing pathological study of the disease in question.
Lets say for instance you have a disease yourself that cuases your bones to grow in an abnormal way compared to other humans. You can talk to a doctor and describe in detail certain problems, pains and restictions you experience. The doctor does xrays, catscans, MRI's etc etc, and takes blood samples. The xrays catscans and MRI's reveal bone growth abnormalities in your legs arms and some of your other long bones like your ribs and even some in your head. He however with ALL OF THIS INFO cant look at the growth plate cells in your bones to see which cell layers in the growth plates are affected. He still cannot take those cells and grow them to see which protein is not expressed or expressed but not properly formed causing the growth plate cells to grow and function improperly. If he could get those cells to see how they are formed then isolate the defective protein or find out that they are not producing a certain protein that should be there then he can look up on Genbank or other gene website databases to see if it is sequenceed, and in the humans it probably is already. He then takes your blood and sequences that gene responsible for that protein and wala your mutation is found. It is much more time consuming and complicated than this but brevity is a must here.
OR
Your doctor takes your blood sample isolates the DNA. Then searches for others like you and hopes to find enough samples (about 50 or more that ARE INDENTICAL IN THE DISEASE) to use brand new data crunching software to hopefully find a general area in the genome that is similar in all the samples, the area could contain hundreds of genes, then you pick genes that have functions that are known to be involved in bone growth, which could be dozens, that each take weeks to sequence, sequence each gene on each sample, and try to find a mutation the exact same in all samples. And they all have to have the EXACT mutation, if not it is not the gene and you start all over with another gene.
Now with horses we dont have near those options.
The Genbank in not complete for the horse, the genome is sequenced but not the identity of genes and where they are. To better understand this concept is it is like making a copy of a 1000 page book, but not reading the the copy, just have it there ready to be read. We do not have horses that can talk, we must go off of examinations, xrays etc to look for physical abnormalities and growth that are the same. We do not have a way to tell all of the horses to donate their blood or be involved in research if they are a dwarf or have produced a dwarf, someone else controls that.
The new data crunching software I discussed above, I am using but I must have enough samples of the exact type and parent samples, that is just halfway looking at this though. I must thoroughly characterize the PHYSICAL description of the disease and show that 100% of all of the type 1 dwarfs with these specific growth abnormalities have this such and such mutation of this such and such gene. Without that I cannot really be sure the gene I find is the cause of all of the type 1 now can I??
Genetic research is much more complicated than most everyone realizes. Remember you are trying to find most likely a single nucleotide mutation in Hundreds of MILLIONS of nucleotides, you better be sure you have the right mutation for that disease, or you are looked at as an idiot, well you also wont get your work published because you will be considered an idiot with no real science to prove your work.
John
