Multiple choice Phenylketonuria is caused due to the deficiency of phenylalanine hydroxylase dihydropteridine reductase homogentisic acid oxidase SAM Reveal answer Fill a bubble to check yourself A Correct answer Explanation Phenylketonuria (PKU) is an inherited metabolic disorder caused by a deficiency of the enzyme phenylalanine hydroxylase, which is required to convert phenylalanine to tyrosine.