Genetic defect

Genetic complementation is a genetic phenomenon that allows two mutations that produce the same phenotype when separate, to produce a wild-type phenotype when combined. This occurs when the mutations are in different genes that contribute to the same function, such as a biochemical pathway.

Overview

In genetics, complementation occurs when two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype (e.g., wingless flies) produce offspring with the wild-type phenotype when mated together. This indicates that the mutations are in different genes (i.e., they are non-allelic). Complementation will not occur if the mutations are in the same gene.

Complementation Test

The complementation test is used to determine whether the mutations in two strains are in different genes. The test involves crossing two strains that have the same mutant phenotype and observing the phenotype of the progeny. If the progeny have the wild-type phenotype, this indicates that the mutations are in different genes, which is referred to as complementation.

Genetic Complementation in Humans

In humans, genetic complementation can occur in compound heterozygotes. These are individuals who have two different mutant alleles of a gene. If the two mutant alleles complement each other, the individual will have the wild-type phenotype.

Applications

Genetic complementation has important applications in genetic engineering and gene therapy. For example, it can be used to identify genes that are involved in a particular biochemical pathway or physiological process. It can also be used to develop therapies for genetic diseases by providing a functional copy of a gene to complement a mutant allele.

See Also

• Genetics
• Mutation
• Phenotype
• Biochemical pathway
• Genetic engineering
• Gene therapy