Can you develops pku later in life?

No, genetic disorder: Phenylketonuria is a genetic disorder and all babies born in the United States are screened for this at birth. the body can't process part of a protein called Phenylalanine. When diagnosed, the treatment is a diet with low protein foods. There are special formulas for babies with "PKU". Both parents must pass on this gene for the baby to have "PKU" Excellent information at www.nihlgov

Not possible: PKU is not a disease you can get.It is based on mistakes in the genes where the protein cannot be metabolized properly.Your body gets 2 copies of the gene, if one is defective, the other can do the work, but if you are born with 2 defective genes you have the problem at birth.Once you start consuming protein, your metabolism can't process the phenylalanine.