PAH and phenylketonuria: Interestingly, as previously published, antibodies raised against Phe assemblies was proven to be valuable diagnostic tool in the case of phenylketonuria (PKU), a common autosomal recessive disorder caused by the genetic malfunction of the phenylalanine hydroxylase enzyme that converts Phe to Tyr, resulting in the accumulation of Phe [14,24,25,26].