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What does pleiotropy reveal about the effects of a single gene?
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heredity
Each offspring is a combination of its two parents, receiving some dominant traits from its mother and others from its father.
Pleiotropy reveals that an organism is not merely an aggregate of independent traits, each determined by a single gene. Instead, it demonstrates that a single gene can influence multiple, distinct phenotypic traits or organ systems.123
In this context, a "trait" is considered an abstraction or a term of convenience, as one gene may have widespread effects across an organism's biology. For example:2
- In animals: The white gene in Drosophila flies is pleiotropic, affecting eye color, the shape of the spermatheca in females, the color of the testicular envelope in males, and the longevity of both sexes.2
- In humans: Many genetic diseases caused by a single defective gene manifest through a variety of symptoms. For instance, Marfan syndrome can result in long, thin extremities and fingers alongside various eye and cardiovascular problems.23
Ultimately, pleiotropy highlights the complex, interconnected nature of genetic expression, where a single mutation can produce diverse clinical manifestations rather than affecting only one isolated characteristic.23