Complementation test

Complementation test is a term from cell biology . It serves as a simple method to localize gene mutations. These genetic changes can be in different genes that participate in the same cell biological process, or on the same gene. The complementation test can often be used to find out whether two recessive mutations that lead to a similarly changed phenotype are alleles of the same gene or not, ie whether the mutants have mutations in the same or in two different genes.

For this purpose, two mutants are crossed with one another and the first subsequent generation (F1) is considered. If the mutation does not appear phenotypically in the F1 generation ( wild-type phenotype), this shows that the mutations were able to compensate each other functionally (complement one another). In this case, they are not alleles of the same gene, but affect two different genes.

If, on the other hand, a changed phenotype appears again in the F1 generation, this means that the mutations were not inherited independently of one another. They can then affect the same gene or have two adjacent gene loci on the same chromosome.