Question

Which of the following disorders in humans is/are due to a defect/deficiency in enzymes involved in the urea cycle?

• A. Alkaptonuria
• B. Argininemia
• C. Argininosuccinic acidemia
• D. Phenylketonuria

Hint:

Urea cycle disorders lead to a buildup of ammonia and include argininemia and argininosuccinic acidemia, while alkaptonuria and phenylketonuria are unrelated to the urea cycle.

Answer 1

The Correct Option is B, C

Step 1: Understanding Urea Cycle Disorders.
The urea cycle is responsible for detoxifying ammonia in the liver. Disorders in the enzymes of the urea cycle result in an accumulation of ammonia, leading to various metabolic issues.
Step 2: Analyzing the Disorders.
- (A) Incorrect. Alkaptonuria is due to a defect in the homogentisate oxidase enzyme, not related to the urea cycle.
- (B) Correct. Argininemia is caused by a deficiency in the enzyme arginase, which is involved in the urea cycle.
- (C) Correct. Argininosuccinic acidemia is caused by a deficiency in the enzyme argininosuccinate lyase, also part of the urea cycle.
- (D) Incorrect. Phenylketonuria is caused by a defect in phenylalanine hydroxylase, unrelated to the urea cycle.
Step 3: Conclusion.
Thus, the correct answers are (B) and (C).