What are examples of lethal genes in animals?

An example of recessive lethal allele occurs in the Manx cat. They process a heterozygous mutation resulting in a shortened or missing tail. Homozygous offsprings for the mutant allele cannot survive birth, when two heterozygous Manx cats are crossed.

In humans, an example of dominant lethal allele is Huntington's disease. A person exhibits this disease when they carry a single copy of a repeat expanded Huntingtin allele on chromosome 4.

Another example of a conditional lethal is favism, a sex-linked inherited condition that causes the carrier to develop hemolytic anaemia when they eat fava beans.

Lethal genes are usually a result of mutations in genes that are essential to the growth or development. Lethal genes can cause death of an organism prenatally or anytime after birth, though they commonly manifest early in development.

Lethal genes in animals include those causing embryonic lethality or severe developmental abnormalities. Examples: "curly coat" in sheep, "Manx" cat tailless trait.