Both BEW and REW are forms of albinoism,and Himalayan as well. Albinos of any kind tend to be less hardy and have problems because of the loss of pigment, however certain rabbit breeds have been carefully bred for healthiness and so breeds like Californians and NZW are hail and hearty. BEW Mini Rex have immune issues because they are all closely related, and need to be bred out to healthier colors. I've noticed that a BEW out of two vienna carriers or that has a vienna carrier as one parent is healthier than a BEW out of two BEW's. Its going to take time to breed them out to healthier lines.
Charlies are a different situation, their problems stem from extreme white spotting. This is seen in other species too, dogs with deafness, horses with gut problems, 'Lethal White Overo' that Frosted mentioned, its a white foal out of high white parents, and there's something wrong with its intestines and it dies. This seems to be part of the problem with Charley rabbits, something wrong with the digestive system.
Now Albino's can have eye problems, and in the case of cats be deaf, but gut problems vary with species and rabbit breed. Its the white factoring that causes most of the deafness problems, such as in Dalmations. Dals are not white dogs with spots, they are black dogs with extreme white spotting and 40% of the breed is estimated to be deaf in one or both ears. So albinoism and high white factoring can cause similiar problems but are not the same.
Merle is also completely different, its a gene that acts like bleach on pigment, diluting the original color. Merle is NOT dominant its an incomplete dominant, meaning that one parent has to be it to get it, and not all puppies will be merles. Merle is NOT a 'Lethal White' gene, double merle puppies do not just die, nor are they always affected, that is completely incorrect. In certain breeds without white factoring like doxies double merles can be born perfectly normal, there were actually a number of AKC Champion double merle doxies before the DCA banned them from the show ring. They had perfectly normal hearing and sight, and had minimal white on them.
Its when you add white factoring to merleing that you get the worst defects, combining these two pigment changers wreaks havoc,causing a lack of eyes, small eyes, blindness and deafness. The breeds most effected are those with high white in them, shelties, danes, aussies, collies. Double merles have been said to have shorter life spans by possibly two years or so, but many are hale and hearty into their teens.
Merle CAN hid, oh yes it can, often an experienced eye can see it but sometimes not- thats why the term 'Cryptic Merle' was coined, because some dogs are merles and show no signs. There is a DNA test for merles now because of this.
In my breed double merles are an important part of the breed and have been very influential, the number one Blue Merle sheltie ever had a DM mother. He's still number one, been dead over 20 years. No, folks who don't know any better shouldn't be breeding them but in dogs one shouldn't breed dilutes to each other either, color dilution Alopecia isn't very pretty. You should know your genetics prior to breeding, regardless of species. Some folks just shouldn't breed anything, or have kids either.
Not picking on anyone, but merle is my color, its what I do, its what I know. Yes horrible defects can occur, but merle alone is not the monster gene, you have to add white factoring to it to really pump up it up, and white factoring can cause deafness and eye problems all on its own- a single merle gene does not do that. White factoring is the bigger threat than merle is.
Look Maggie, I made paragraphs!!
