<prompt> Lesch-Nyhan syndrome is due to the deficiency of which enzyme?Glucose 6- phosphataseGlutathione reductasePRPP glutamyl-amidotransferaseHypoxanthine-guanine phosphoribosyl transferase  <response>: D Hypoxanthine-guanine phosphoribosyl transferase LESCH-NYHAN SYNDROMEis a sex-linked metabolic disorder since the structural gene for HGPRT is located on the X-chromosome. It affects only the males and is characterized by excessive uric acid production often gouty arthritis, and neurological abnormalities such as mental retardation, aggressive behaviour, learning disability etc. The patients of this disorder nave an irresistible urge to bite their fingers and lips, often causing self-mutilation. 