Term: lethal gene: any gene that has an effect that causes the death of the organism at any stage of life
Broader: gene: (genetics) a segment of DNA that is involved in producing a polypeptide chain; it can include regions preceding and following the coding DNA as well as introns between the exons; it is considered a unit of heredity | Unrelated: coolant: a fluid agent (gas or liquid) that produces cooling; especially one used to cool a system by transferring heat away from one part to another