Darrin writes >As near as I have been able to ascertain ? the genes for "most causes >of deafness" are recessive, and only brought out in crossbreeding >parents with the recessive gene, thus increasing the likelihood of the >recessive becoming the only gene pair, and therefore dominant. Actually Waardensburg is known to be dominant, and I believe others such as KIT are too. The problem is the variable expression of these genes--it has the effect of hiding the defect in some individuals. Another slight correction: having a pair of recessive genes does not make it "dominant", it simply becomes expressed. Darrin also writes >However, my point was, ( and this is much easier with ferrets then some >other animals, as they have a lot of kits per litter and statistics are >easier per large litters). If ANY of the subsequent kits are deaf.. >then NONE of the others from that litter should be bred as they are all >now (or mostly) now obviously carriers. and >As soon as there is any incidence of deafness, the entire bloodline >should be shut down. But your point is absolutely correct and well stated! Linda Iroff International Ferret Congress http://www.ferretcongress.org [Posted in FML issue 4670]