Question

Meenu is suffering from a genetic disorder in which phenylpyruvic acid and its metabolites accumulate in blood. It causes impairment of nervous tissues. Which enzyme deficiency has caused this disorder in Meenu?

Hint:

PKU is a classic example of pleiotropy, where a single gene mutation affects multiple phenotypic traits.

Answer 1

Step 1: Identify the disorder from the symptoms.
The question states that phenylpyruvic acid and its metabolites accumulate in the blood and it causes damage to nervous tissues. These symptoms are characteristic of the genetic disorder known as Phenylketonuria (PKU).

Step 2: Understand the metabolic defect.
In normal metabolism, the amino acid phenylalanine is converted into another amino acid called tyrosine. This conversion is essential for normal metabolic processes in the body.

Step 3: Identify the missing enzyme.
The conversion of phenylalanine into tyrosine requires the enzyme Phenylalanine hydroxylase. When this enzyme is absent or deficient, phenylalanine cannot be properly metabolized and instead forms phenylpyruvic acid and other harmful metabolites that accumulate in the blood.

Step 4: Explain the effect of the deficiency.
The accumulation of phenylpyruvic acid is toxic to the brain and nervous system. This leads to mental retardation, developmental delay, and impairment of nervous tissues if not treated early.

Final Answer:
The disorder is caused due to deficiency of the enzyme Phenylalanine hydroxylase.