Phenylketonuria (PKU) is a genetic disease caused by mutation of the PAH gene, which normally produces the enzyme phenylalanine hydroxase. This enzyme is essential for the conversion of the amino acid phenylalanine into tyrosine. Without the enzyme, phenylalanine builds up in the blood and tissues of various body regions. It can produce severe skin discolorations and foul odor, but also intellectual disabilities and behavioral problems. Some people may experience only one type of PKU symptoms and not the others. PKU is an example of

The correct answer is - Pleiotropy.

Explanation:

Pleiotropy is the number of disorders where multiple, and unrelated organ systems are affected in the body of an individual. Phenylketonuria (PKU) is the most cited example of pleiotropy in humans.

It is an inherited disorder that is caused by a deficiency of the enzyme phenylalanine hydroxylase due to mutation in the PAH gene, This enzyme is necessary to convert the essential amino acid phenylalanine to tyrosine. By this disorder, multiple organ systems are affected such as severe skin discolorations and foul odor, and other intellectual disabilities and behavioral problems.