Which type of genes are responsible for causing abnormal development and the death of an individual?

Lethal genes are responsible for causing abnormal development and can lead to the death of an individual, particularly during the early stages of life, such as embryonic development. These genes can produce effects that are lethal when present in certain genotypes. For example, if an individual inherits a particular lethal allele in a homozygous state, the organism may not survive to birth or may lead to early postnatal death. In some cases, lethal genes may also manifest in traits that disrupt normal physiological processes, ultimately impacting the viability of the organism.

In contrast, dominant genes could potentially lead to conditions that are expressed phenotypically, but they do not necessarily induce lethality in every instance. Similarly, recessive genes might cause disorders only when an individual inherits two copies of the allele, which does not inherently indicate that these genes will cause death.

Suppressor genes, on the other hand, are those that can inhibit the expression of other genes and do not directly contribute to abnormal development or mortality in the same way lethal genes do. Thus, lethal genes are uniquely characterized by their ability to result in non-viability or severe developmental abnormalities that can lead to death.