Gene, zygotic lethal: A gene that is fatal for the zygote, the cell formed by the union of a sperm and an egg. The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene kills prenatal development at its earliest point. A zygotic lethal gene is a mutated version of a normal gene that is essential to the survival of the zygote.
Reviewed on 9/7/2018