A three and half-year-old male child, who presented with characteristic self-mutilating behavior. He had history of developmental delay, difficulty in social interaction, attention deficit and features of autism. His serum blood biochemistry was normal except for low hemoglobin levels and raised serum uric acid levels. Which of the following enzyme is deficient?

The above features suggests diagnosis of Lesch-Nyhan syndrome is X-linked recessive disorder associated with a viually complete deficiency of Hypoxanthine-guanine phosphoribosyltransferase (HGP). This deficiency results in an inability to salvage hypoxanthine or guanine, from which excessive amounts of uric acid, the end product of purine degradation, are produced. It also causes increased PRPP levels and decreased IMP and GMP levels. Clinical features: Intellectual disability Self-mutilation Aggression Hyperuricemia Gout Treatment: Allopurinol Febuxost Reference: Harpers illustrated biochemistry 30th edition