different types of pku
People with PKU can have different levels of PAH deficiency, resulting in differences in Phe levels and symptoms. Different PKU levels are sometimes classified as classic PKU, moderate or variant PKU, mild PKU, or hyperphenylalaninemia.3. Based on blood Phe levels at diagnosis, there are 4 levels of PKU severity 3 :or a person to have PKU, both the mother and the father must pass on the mutated phenylalanine hydroxylase (PAH) gene. Each parent is a âcarrierâ because he or she carries one copy of the mutated, diseaseÂ­âcausing gene and one copy of the nonmutated gene. People who are carriers of the PKU gene have no known symptoms.