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NEETZoologyPrinciples of Inheritance and Variation

What causes the disease phenylketonuria?

Options

  1. AMutation in multiple genes
  2. BEnvironmental factors
  3. CMutation in the gene that codes for phenylalanine hydroxylase
  4. DHormonal imbalance

Correct answer

C. Mutation in the gene that codes for phenylalanine hydroxylase

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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