My idea on a mutation is uneven limbs, there would be two types. (Frontal and Dorsal)
The frontal would just mean the front two paws would be shorter than the back two, and Dorsal would be the opposite.

Lions with this mutation would also be skinny, because of the energy it takes to keep themselves upright and not fall over.

This could possibly be a breeding result of dwarfism.

It will be visible from birth too!
What are your thoughts?