A 4-year-old male with mental retardation, self-mutilation, and hyperuricemia is likely to have a deficiency of an enzyme involved in the:: (A) Conversion of homogentisic acid to methylacetoacetate, (B) Degradation of galactocerebroside, (C) Breakdown of branched-chain amino acids, (D) Recycling of guanine and hypoxanthine
Answer is D. Adenosine deaminase is an enzyme that is deficient in individuals with the autosomal recessive form of SCID, and hypoxanthine-guanine phosphoribosyl transferase (HGPRT), an enzyme of the purine salvage pathway for recycling guanine and hypoxanthine that is deficient in individuals with the X-linked recessive disorder Lesch-Nyhan syndrome.