Define the term: Pleiotropy.

(N/A) Pleiotropy is a genetic phenomenon in which a single gene influences two or more seemingly unrelated phenotypic traits.
In this case,the product of a single gene can produce multiple phenotypic effects in an organism.
An example of pleiotropy is the disease phenylketonuria $(PKU)$,which is caused by a mutation in a single gene that codes for the enzyme phenylalanine hydroxylase,leading to multiple symptoms such as mental retardation and reduction in hair and skin pigmentation.