How many kittens in an affected litter will normally have CH?

The severity level of CH and number of kittens in a litter born with CH depends on how developed the kittens were in utero when the development of the cerebellum was stunted or stopped. It is perfectly normal for one, all, or any number of kittens in a litter to have CH and for their severity levels to vary.  For instance, one kitten might be born with severe CH and her siblings could be mild or not have CH at all.