Phenylketonuria is due to the deficiency of:

(B) Phenylalanine hydroxylase (PAH)[?]PHENYLKETONURIAoClassical is HyperPhenylaminemia. Other can be due to defective biopterin cofactoroBiosynthesis-GTP cyclohydrolase I-6-pyruvoyl-tetrahydropterin synthase - Dihydropterin reductase.[?]Biology of PhenylketonuriaoPhenylketonuria or PKU is the inability of the body to Metabolize pheynlamine.oPhenylaline builds to toxic levels in the tissues, particularly damaging the nervous systemoPKU is a chronic disease, but it is possible to greatly reduce the probability of further damage by following a strict low-protein dietoPKU is autosomal recessive and carried on chromosome 1 2[?]Symptoms: Often have lighter skin, hair, and eyes than brothers or sisters without the disease.oOther symptoms include:-Eczema-Recurrent vomiting-Jerking movements in arms and legs-Tremors & Mood disorders, MicrocephalyoA birth defect that causes an amino acid called phenylalanine to build up in the body.oPKU is an autosomal recessive metabolic genetic disorder.oPKU is characterized by homozygous or compound heterozygousmutations in the gene for the hepatic enzyme phenylalanine hydroxylase (PAH), rendering it nonfunctional.oThis enzyme is necessary to metabolize the amino acid phenylalanine (Phe) to the amino acid tyrosine (Tyr). When PAH activity is reduced, phenylalanine accumulates and is converted into phenylpyruvate (phenyl ketone), which can be detected in the urine.oPAH gene is located on chromosome 12 in the bands 12q22-q24.1.oMore than 400 disease-causing mutations have been found in the PAH gene.INBORN ERRORS OF AMINO ACID METABOLISMS DISORDERSDisorderEnzyme Deficiency*. PhenylketonuriaPhenylalanine hydroxylase*. AlkptonuriaHomogentistate 1, 2- Dioxygenase complex*. Homocystenuria Type IDefect in cofactor binding site of cystathionine synthase*. Homocysteinuria Type IIMethylene THF Reductase Decrease*. Cysteinuria Type ICystathionine synthase*. CystathioninuriaCystathionase*. Tyrosinemia Type ICystathionine synthase*. Tyrosinemia Type IITyrosine Aminotransferase*. Tyrosinemia Type IIIPara-hydroxyphenylpyruvate dioxygenase*. AlbinismTyrosinase