Re: [pyrnet] Pyr eyes

[JGentzel@aol.com]

In a message dated 12/20/00 9:21:20 AM Pacific Standard Time, 
lmweisser@olywa.net writes:



> .  If we know that fact but nothing
> absolute about the parents or the intervening generations, then the
> individual dog has a 50% chance of carrying.  




Always presuming the Sire or Dam that has the affected or carrier in its 
pedigree is at least a carrier.  

Statistical probability though tells us that purely by chance the percentage 
of chance that the recessive gene from only one generation, with no 
interviening recessive genes show up from other sources, transmits down is 
reduced each generation.  For example with 10 puppies in generation 1, 
probability is 5 will be affected and 5 will be clear.  The next generation 
the probability from the first generation carrying the affected animal is 
reduced by 50%, so now if each of the 10 pups in generation 1 had 10 puppies 
for a total of 100 puppies the probability is that only 25 puppies or 25% 
will be affected or be a carrier in generation 2.  That means that there is a 
75% probality in generatioin 2 of dogs being clear.  The minute a dog is 
confirmed in any generation of being a carrier or affected, the probability 
immediately goes back up to at least 50%.  This is the basis behind the 
Malamute people using f!
ormulas to calculate the numbers they use that has and 
Is meeting with sucess in getting a reduction in the number of Dwarfs.  
Probability is useful in groups but not necessarily useful with an 
individual, but it is harsh to assume that all descendants are always 50% at 
risk and is not really true.  An ever deminsihing number of descendants each 
generation will be at risk of 50%.  If the 50% always was true, most us 
should ethically always disclose to all our puppy buyers that they have a 50% 
change of having things like Dwarfs, etc.  I doubt there is a litter from 
show stock in the USA that does not have a dwarf carrier behing it somewhere. 

Joe