Question

Match List I with List - II.

List - I	List - II
A. Hyperammonemia type I	I. Arginase
B. Hyperammonemia type II	II. Arginosuccinate synthase
C. Citrullinemia	III. Ornithine transcarbamoylase
D. Hyperargininemia	IV. Carbamoyl phosphate synthase

Choose the correct answer from the options given below:

• A. A-I, B-II, C-III, D-IV \
• B. A-IV, B-III, C-II, D-I \
• C. A-II, B-III, C-I, D-IV \
• D. A-III, B-II, C-I, D-IV

Hint:

Type I corresponds to Enzyme 1 (Carbamoyl Phosphate Synthase). Type II corresponds to Enzyme 2 (Ornithine Transcarbamoylase).

Answer 1

The Correct Option is B

Step 1: Concept The urea cycle converts toxic ammonia into non-toxic urea for excretion. Genetic deficiencies in any of the five core enzymes of this cycle lead to specific clinical disorders characterized by hyperammonemia.

Step 2: Meaning Disorders are named based on the specific enzyme mutation that causes intermediates to accumulate in the blood and tissues.

Step 3: Analysis * Hyperammonemia type I (A) is caused by a deficiency in the first mitochondrial enzyme of the cycle, Carbamoyl phosphate synthase I $\rightarrow$ (A-IV). * Hyperammonemia type II (B) is an X-linked disorder caused by a deficiency in Ornithine transcarbamoylase $\rightarrow$ (B-III). * Citrullinemia (C) results from a defect in Arginosuccinate synthase, which prevents the conversion of citrulline and aspartate into arginosuccinate $\rightarrow$ (C-II). * Hyperargininemia (D) is caused by a deficiency in the final enzyme, Arginase, leading to elevated arginine levels $\rightarrow$ (D-I).

Step 4: Conclusion The exact mapping is A-IV, B-III, C-II, D-I, matching option B. Final Answer: (B)