Bet, this in not correct. It is really important to understand that the mode of inheritance relates to the individual, not the group as a whole. Each pairing of egg and sperm is an individual event.
Also could I mention that ,
If two Carriers are Mated of a Disease,SM, MVD ,statiscally,
50% of the Litter will be Carriers.
25% of the Litter will be Affected .
25% of the Litter will be OK.
For a single recessive gene mode of inheritance, if both parents carry one recessive and one dominant gene, each puppy has the following:
25% chance of not receiving the recessive gene from either parent;
50% chance of receiving one recessive gene from one parent;
25% chance of receiving both recessive genes from both parents.
This difference is huge. In this situation, it is quite possible that all the puppies in a litter could receive both affected genes and or that none could. (The same holds true for the sex of a puppy. Each puppy has a 50/50 chance of being male or female. That doesn't mean that 1/2 the puppies in each litter will be male and half will be female.)
Looking at the variability of symptoms and age of onset of SM, it wouldn't surprise me at all if there were several "types" of SM, each caused by different genes and/or gene combinations. Research is crucial to finding the answers.
Last edited by Jay; 11th November 2009 at 06:40 PM.
J. and pups, Gem, Monty, Harley and Sapphire