Deficiency of enzyme homogentisic acid oxidase leads to.

Options

A. phenyl ketonuria
B. alkaptonuria
C. albinium
D. polydactyly

Answer

**Step-by-Step Solution:**

1. **Identify the Enzyme and Its Function**: The enzyme in question is homogentisic acid oxidase. This enzyme is crucial for the breakdown of the amino acids phenylalanine and tyrosine.

2. **Understand the Role of the HGD Gene**: The HGD gene is responsible for the synthesis of homogentisic acid oxidase. When this gene is mutated or deficient, the enzyme is not produced adequately.

3. **Consequences of Enzyme Deficiency**: When there is a deficiency of homogentisic acid oxidase, the body cannot effectively break down homogenic acid, which is a byproduct of phenylalanine and tyrosine metabolism.

4. **Accumulation of Homogenic Acid**: Due to the deficiency, homogentisic acid accumulates in the body. This accumulation leads to various health issues, particularly affecting the cartilage and skin.

5. **Symptoms and Conditions**: The buildup of homogentisic acid in tissues causes them to turn black, a condition known as alkaptonuria. Additionally, prolonged accumulation can lead to arthritis.

6. **Distinguish from Other Conditions**: It is important to differentiate alkaptonuria from other conditions mentioned in the question:
- **Phenylketonuria** is caused by a deficiency in an enzyme that breaks down phenylalanine, not homogentisic acid oxidase.
- **Albinism** is related to melanin production and is not caused by the deficiency of this enzyme.
- **Polydactyly** refers to the presence of extra fingers or toes and is unrelated to the metabolism of amino acids.

7. **Conclusion**: The deficiency of the enzyme homogentisic acid oxidase specifically leads to the condition known as alkaptonuria.

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