A ten-year-old child with aggressive behavior and poor concentration is brought with presenting complaints of joint pain and reduced urinary output. Mother gives history of self-mutilative behavior stating that he tends to mutilate his fingers. Which of the following enzymes is likely to be deficient in this child?

HGP is a transferase that catalyzes the conversion of hypoxanthine to inosine monophosphate and guanine to guanosine monophosphate. This reaction transfers the 5-phosphoribosyl group from 5-phosphoribosyl 1-pyrophosphate (PRPP) to the purine. HGP plays a central role in the generation of purine nucleotides through the purine salvage pathway