There are a number of videos on Youtube that show the effect of Cerebellar Hypolpasia in cats. Mimi has this condition but has adapted (as they all do) and is a loving and active cat (although she can't jump and does have balance problems). Cats with CH will have a natural lifespan.
This is Charley. It could be Mimi - just imagine a little grey cat with amber eyes and a pot belly!