Biochemistry Defect in alkaptonuria is: A Defect in phytanic acid oxidase B Absence of homogentisic acid oxidase C Deficiency of homogentisic acid oxidase D Deficiency of phenylalanine hydroxylase 💡 Explanation Defect in alkaptonuria is: ✓ Correct Answer: C. Deficiency of homogentisic acid oxidase