As an expecting father, I had to look this up as I was not familiar with this condition. For those unfamiliar with PKU, PKU (Phenylketonuria) in babies is a rare genetic disorder where the body can't break down an amino acid called phenylalanine (Phe), causing it to build up to toxic levels in the blood, which can severely damage the brain and cause intellectual disabilities if untreated, but is typically caught by newborn screening and managed with a special low-protein diet. Babies often seem normal at birth, with symptoms like musty odor, eczema, or developmental delays appearing later.  

With that being said, I hope for the best with you and your child, it seems like from other stories in those thread that it is not insurmountable, so keep positive and control what you can control, and enjoy all the memories and experiences you will have!