Question

Explain pleiotropy with reference to phenylketonuria.

Answer 1

Pleiotropy involves the ability of a gene to have multiple phenotypic effects, because it influences a number of characters simultaneously. The genes are called pleiotropic genes.

Example:

A mutated recessive gene for the disorder phenylketonuria produces multiple phenotypic expressions-mental retardation and reduction in hair and skin pigmentation. Phenylketonuria is due to autosomal recessive trait. It lacks an enzyme to convert phenylalanine to tyrosine. Phenylalanine accumulates in the body. Accumulation in brain results in mental retardation.