Hello fine folk.

I know this can be present in cats, but I'm not sure about lions, but I still wanted to suggest it. Cerebellar Hypoplasia (CH) affects the nervous system. If you're interested more in the specifics, feel free to search it up.

CH, and how it'll affect the cub
CH is not fatal on its own, but it can cause several hinders in a cat's quality of life. This lioness would not be able to leave by themselves, of worry of them needing help. This means no patrolling, hunting, crowning, etc. You would get unique flavor text though. Another thing is they have a higher mortality rate. As cubs, if not protected they have a low chance of survival. If they are protected, they may not be at 100%, though I'm unsure about this.

This also has the possibility to be a lethal adult mutation. As an adult, as they get older their eye-sight gets worse, and their brains are not as sharp. They could easily end up in a stampede.

Extras
Its most often contracted when a pregnant cat gets infected with something. I'm not suggesting we add what they're infected with, but instead just some flavor text. The flavor text could be universal, or different based on the personality. Here's a basic example.

[LIONESS] felt a bit under the weather today. You told her not to worry because you bet her cubs would be alright.

CH makes the cat wobble, hence the name "Wobbly Cat Syndrome", as the cats don't have full control over their nervous system. I suggest this would make the cub pose special, with its head lower as it tries to keep balance.