Not everything is encoded redundantly. Try changing CGA to TGA in one of the exons of PAX6. In humans, this change will result in aniridia, the lack of an iris, an unstable corneal epithelium, and other problems. This is just one example, the one I'm familiar with. There are many other single nucleotide polymorphisms that can cause big changes.
Comments
Not everything is encoded redundantly. Try changing CGA to TGA in one of the exons of PAX6. In humans, this change will result in aniridia, the lack of an iris, an unstable corneal epithelium, and other problems. This is just one example, the one I'm familiar with. There are many other single nucleotide polymorphisms that can cause big changes.