Pleiotropy occurs when a single mutation or gene/allele affects more than one phenotypic characteristic.

Which situations are examples of pleiotropy?

One example of pleiotropy is Marfan syndrome, a human genetic disorder affecting the connective tissues. This disease commonly affects the eyes, heart, blood vessels, and skeleton. Marfan Syndrome is caused by a mutation in a human gene resulting in pleiotropy.

How does pleiotropy happen?

Pleiotropy (from Greek πλείων pleion, "more", and τρόπος tropos, "way") occurs when one gene influences two or more seemingly unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene.