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NEETZoologyPrinciples of Inheritance and Variation

What are the phenotypic expressions of phenylketonuria?

Options

  1. AMental retardation and hair loss
  2. BMental retardation and reduction in hair and skin pigmentation
  3. CReduced vision and skin pigmentation
  4. DHair loss and reduced vision

Correct answer

B. Mental retardation and reduction in hair and skin pigmentation

Step-by-step solution

We have so far seen the effect of a gene on a single phenotype or trait. There are however instances where a single gene can exhibit multiple phenotypic expressions. Such a gene is called a pleiotropic gene. The underlying mechanism of pleiotropy in most cases is the effect of a gene on metabolic pathways which contribute towards different phenotypes. An example of this is the disease phenylketonuria, which occurs in humans. The disease is caused by mutation in the gene that codes for the enzyme phenylalanine hydro

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