<s>[INST] context: Lesch-Nyhan syndrome (LNS), also known as Nyhan syndrome and juvenile gout, is a rare inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGP), produced by mutations in the HP gene located on the X chromosome. LNS affects about one in 380,000 live bihs. The disorder was first recognized and clinically characterized by medical student Michael Lesch and his mentor, pediatrician William Nyhan, who published their findings in 1964. The HGP deficiency causes a build-up of uric acid in all body fluids. This results in both hyperuricemia and hyperuricosuria, associated with severe gout and kidney problems. Neurological signs include poor muscle control and moderate intellectual disability. These complications usually appear in the first year of life. Beginning in the second year of life, a paicularly striking feature of LNS is self-mutilating behaviors, characterized by lip and finger biting. Neurological symptoms include facial grimacing, involuntary writhing, and repetitive movements of the arms and legs similar to those seen in Huntington&;s disease. The etiology of the neurological abnormalities remains unknown. Because a lack of HGP causes the body to poorly utilize vitamin B12, some boys may develop megaloblastic anemia. [/INST] question: Lesch-Nyhan syndrome is caused by the deficiency of | options: A: Folic acid B: Carbamoyl phosphate synthetase II C: UMP synthase D: HGP | answer: D </s>