Wild Type in genetics

You will often see the term wild type used in genetics. This can be used to refer either to a wild type allele or to a wild type phenotype (which is coded by the wild type allele). The wild type allele refers to a common allele found in a natural population or to a common lab genotype (when the wild type allele is homozygous) generated from the natural population. It is often used as a reference genotype, with the genotype that it is compared to being referred to as a mutant genotype.

The use of wild type is not intended to imply any superiority to a mutant, it is simply a useful reference. It did arise during a time when geneticists tended to think there was not much genetic variation in populations but we now know that variation is very common so there is usually not a single wild type allele. However, we still use the term for a reference genotype - or allele - that originally came from a natural population. In this context, reference means a genotype (or phenotype) that is used as a point of comparison in experimental studies. A mutant is then something that differs from the wild type in some particular trait and the point of many genetic experiments is to understand the basis for the difference between mutant and wild type. For example, we search for answers to basic questions such as: what gene(s) contributes to the difference between mutant and wild type? What is the nature of this genetic difference? What protein is coded by this gene? How does the mutation affect the function of the protein? What other proteins interact with this one and what basic biological function(s) do they contribute to? Such work can help to further our understanding of the basic biology of that trait.

It is also important to note that wild type does not imply dominant! Whether or not a mutant allele is recessive or dominant to wild type depends on many biological factors, and we have to observe the phenotype of the heterozygote to determine if a mutant is recessive to wild type.