You'd think this mutation would be fairly harmless, however it can cause severe deformities in the jaw and mouth. Couldn't find a decent non-gross picture so if you really wanna see, be aware it's not pretty and search for yourself.

This mutation would appear at birth and be lethal. Cub dies at one month due to starvation/malnutrition. Lineart may slightly change or a whole new might be created.

Critique/reasoning welcome!