Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A dominant lethal allele is a genetic variant that causes the death of an organism when present in a single copy. Such lethality typically occurs early in development, preventing the individual from surviving to reproduce.
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Inheriting one copy of a dominant lethal allele results in death, often before reproductive age.
Huntington's disease is an example of a condition caused by a dominant lethal allele, where symptoms typically appear after reproductive age.
Dominant lethal alleles are rare because they eliminate themselves from the population by causing early death.
These alleles can persist in populations if they have late-onset effects, allowing carriers to reproduce before dying.
Researchers study dominant lethal alleles to understand genetic diseases and developmental processes.
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Related terms
Recessive Lethal Allele: A genetic variant causing death only when two copies are inherited.
Autosomal Dominant Inheritance: A pattern where one copy of an altered gene is sufficient to cause a trait or disorder.
Homozygous: Having two identical alleles for a particular gene.