PKU question

Hello,

My daughter is three months old. We’re currently waiting to get tests done to see if she has PKU or is just a carrier. (It’s one or the other, she has the gene) I know if you don’t treat it you can get brain damage and other stuff, and it’s usually discovered in the first couple weeks of life.

my question is, since she’s already three months old, (assuming she has it) could she be getting brain damage or other complications by this point? I don’t have any diet restrictions and she is 100% breastfed. I asked her doctor if there’s anything I should be doing to prevent complications if she does have PKU while we’re waiting for confirmation, and they said just make sure she eats often.

Please help!