Lethal genes can be recessive, as in the aforementioned mouse experiments. Lethal genes can also be dominant, conditional, semilethal, or synthetic, depending on the gene or genes involved.

What does it mean if a gene is lethal?

: a gene that in some (such as homozygous) conditions may prevent development or cause the death of an organism or its germ cells. — called also lethal factor, lethal mutant, lethal mutation.

What is a dominant lethal mutation?

A dominant lethal mutation is one which occurs in a germ cell and results in the death of the fertilized egg or developing embryo. Dominant lethals are generally accepted to be the result of both structural and numerical chromosomal aberrations.