Question

What are examples of lethal genes in animals?

Answer 1

Hint: Genes are defined as a set of instructions that determine the complete structure of an organism, which includes its appearance, how it survives, and how it behaves in its environment. Genes are made of a particular substance which is known as deoxyribonucleic acid, or DNA. They basically give instructions to a living being to make molecules known as proteins.

Complete solution:
Lethal genes, which are also called lethal alleles, are alleles which cause the death of an organism, which carries these lethal genes.
The best example of an organism in which recessive lethal allele occurs is that of the Manx cat. They usually process a heterozygous mutation which results in a shortened or missing tail. Homozygous offspring, specifically for the mutant allele, cannot survive birth when two heterozygous Manx cats are crossed.
In humans, the perfect example of a dominant lethal allele is Huntington's disease. A person generates this disease when they carry only a single copy of the repeat expanded Huntingtin allele on chromosome 4.
Another example of a conditional particular condition is favism, which is a sex-linked inherited condition which causes the carrier to get a hemolytic anaemia when they eat the fava beans.
Lethal genes are generally a result of mutations which take place in the genes that are essential for growth and development. Lethal genes can even cause death of an organism anytime after birth, though they usually manifest very early in the development.

Note:
Just like lethal alleles, there are some alleles which are responsible for the hemophilia and these are known as semilethal or sublethal genes. They are known by this name as they cause the death of some of the organisms with the affected genotype.