Phenylketonuria (PKU) is inherited disease that is characterised by

Options

A. Elimination of gentisic acid in urine
B. Increased occurrrence of phenylalamine in blood nad tissues
C. Elimination of sugar in urine
D. Decrease in phenylalanine in blood and tissues.

Answer

### Step-by-Step Solution:

1. **Understanding Phenylketonuria (PKU)**:
- PKU is a genetic disorder that affects how the body processes a specific amino acid called phenylalanine.

2. **Genetic Basis**:
- PKU is inherited in an autosomal recessive manner. This means that an individual must inherit two copies of the mutated gene (one from each parent) to exhibit the disease.

3. **Enzyme Deficiency**:
- The disorder is characterized by a deficiency in the enzyme phenylalanine hydroxylase (PAH), which is crucial for the metabolism of phenylalanine.

4. **Consequences of Enzyme Deficiency**:
- Due to the lack of PAH, phenylalanine accumulates in the body because it cannot be converted into tyrosine, another amino acid.

5. **Metabolic Byproducts**:
- The excess phenylalanine is then converted into phenylpyruvate (also known as phenylketone), which can be detected in the urine of affected individuals.

6. **Identifying the Characteristic of PKU**:
- The key characteristic of PKU is the increased levels of phenylalanine in the blood and tissues, leading to various health issues if not managed properly.

7. **Conclusion**:
- Therefore, the correct answer to the question is that phenylketonuria is characterized by the increased occurrence of phenylamine in blood and tissues.

### Final Answer:
- **Increased occurrence of phenylamine in blood and tissues** (Option 2).

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