This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Integrated QBank, Subject name: Unknown
A 1-year-old child presented with involuntary movements which were choreoathetoid in nature, spasticity, dystonias and intellectual disability. The speech of the child was dysahric and mother also gave history of compulsive biting. Some inherited disorder was suspected. The child was normal at bih. Lab findings revealed increased uric acid levels. The enzyme deficient in the above condition catalyses which of the following reactions. 
Select and explain. 
A. Guanine to GMP, B. GMP to guanine, C. Adenine to AMP, D. AMP to adenine
A: Guanine to GMP
Answer: A: Guanine to GMP 
Explanation: This is a case of Lesch-nyhan syndrome due to the deficiency of enzyme HGPase.