hiya there. . . research here for the litter: manx syndrome is a group of problems that causes a cat, or any other creature born into the world with it, to have a lack of a tail and increased issues near the hind of the animal. this is caused at birth when the formation of the animal isn't proper and can cause the bottom part of their backbone to bundle up nerves. some symptoms include a lack or shortened tail, a slightly wobble or stumble when they walk, along with... no nicer way to put it, bowel troubles^^ in severe cases, a cat may become paralyzed later in their life due to this. or the muscles in the hind legs of the cat may become slightly more weakened. this trait in a cat is a dominant trait, meaning that if the cat were to ever have a litter of biological kits, the kits would also most likely carry some form of this disability. thank you.