Most of the mutants mentioned above were lethal mutations, which may be associated with lethal genes.

上述突变体大多为致死性突变，推测其可能与致死性基因突变有关。

youdao

It is said all people carry 5-6 lethal genes as well as numerous genes that can cause the development of many disease conditions.

就像常被人说的带有5 - 6个致命的基因人是导致许多基因和造成疾病的发作的缘故。

youdao

The genes of mice and human beings have been conserved by evolution, partly because changes to genes are lethal.

FORBES: Scientists Ask: What Is A Gene, Anyway?

Gene therapy's tantalizing attraction is that a single treatment has the potential to cure lethal diseases by enabling normal genes to take over for defective ones.

WSJ: The Future of Medicine Is Now: Medical Innovations