What would need to be missing/altered for you not to consider yourself you anymore?

To not be considered 'you' i suppose (if possible) that you would need to have your identity altered and your DNA, as well as your memories and emotions.

Any main personality trait that separates one person from another. Changes in the least details can have a snowball effect, and cause great change, in general, in a person; therefore you can't consider them to be 'themselves' anymore.

Personally, I think if I were not so picky, I wouldn't be myself!

Memory. It's what holds our identity together. But I suppose if I lost it, it would be more a feeling of not knowing who I am, rather than not being myself anymore.

Human sympathy, Wisdom and simplicity

My brain, my memories and/or my beliefs and ethics

Chop off, or modify any part of 'me' and I, mySelf, remains... unaltered and unaffected.

My puss