Is the "Merle" gene bad in all breeds?

I know that the merle gene is bad in Chihuahuas because it can genetically cause blindness and deafness, as well as making the Chis grow larger than they should (because of mixed breeding). My question is that I know other breeds such as the Australian Shepherd and the Dachshund (called Dapple) also have the "merle gene" bred into their bloodlines. Does the merle gene have the same effects on these breeds as it does on Chihuahuas? (Other than growing larger than expected for Chihuahuas). Thanks all.