PAH enzyme is one of the most vital enzymes in protein metabolism of the body. The enzyme has been found in various organisms and thus proves it has evolved along with speciation.PAH catalyses hydroxylation of the aromatic side of the phenylalanine to generate Tyrosine (4-hydroxyphenylalanine), one of the 20 standard amino acids that exist. The buildup of excess phenylalanine in the body due to deficiency of PAH causes a condition called Phenylketonuria which causes significant nerve damage. The condition Phenylketonuria is caused due to genetic mutation in PAH gene (Cr.12 )in an individual which can cause PAH enzyme deficiency. The purpose of this analysis was to use the existing Bioinformatics databases to draw relevant similarities of PAH of Homo sapiens and other organism using BLAST , MSA(Multiple Sequence Alignment) and phylogenetic relation while proposing the use of gene therapy using the data derived to cure Phenylketonuria

Keywords : PAH enzyme , PKU disease , Gene therapy for PKU.