Lesh-Nyan syndrome is due to deficiency of: (Repeat)
Ans: A (HGPRTase) Ref: Harper's Illustrated Biochemistry, 29th edition. Page 335, 339 & 742Explanation:Lesh-Nyhan SyndromeThis syndrome is characterized by:HyperuricemiaUrolithiasisSelf mutilationCNS manifestationsExtrapyramidul involvement (Choreathethosis, Dystonia, Ophisthotonus)Enzyme DefectHypoxanthine-guanine Phosphoribosyl Transferase (HGPRTase).This enzyme is involved in purine salvage it converts hypoxanthine to inosine mono phosphate (IMP).In absence of this enzyme intracellular PRPP levels will be elevated.Mutation in gene producing HGPRTase may be due to deletion, frame shift mutation, base substitutions or aberrent mRNA splicing.Note: Salvage reactions require less energy than the de novo synthesis.
HGPRTase
CPS I
CPS II
PRPP synthetase
Metabolism of Purines and Pyrimidines