- In absolute lethality individual die in embryonic stage. (ex:Yellow fur in mice)
- In sublethality individual dies before reproductive maturity. (Sickle cell anemia)
|Sickle cell anemia|
- In delayed lethality individual dies after sexual maturity.
- Dominant lethals- Whose lethal effects occur in heterozygous individuals.
- Recessive lethals- If lethality is due to homozygousity for a recessive allele, the allele is called a recessive lethal. The phenotypic ratio is always converted from 3:1 to 2:1.