Question

How can epistasis explain incomplete penetrance?

Short answer

Epistasis can explain incomplete penetrance as it is a scenario where the activity of one gene (epistatic gene) controls or affects the phenotype of another gene (hypostatic gene). Therefore, even if an individual carries a gene that is typically associated with a certain trait, the presence or influence of an epistatic gene might prevent the expression of this phenotype, leading to incomplete penetrance.

Step-by-step solution

Understanding Epistasis

Epistasis is a situation where the expression of one gene is controlled or affected by another gene. The gene whose phenotype is expressed is called the epistatic gene, while the gene whose expression or phenotype is suppressed is the hypostatic gene.

Understanding Incomplete Penetrance

Incomplete penetrance happens when an individual has a certain genotype but doesn't express the expected phenotype. This means that even if an individual carries a gene associated with a particular trait, this trait may not become a noticeable part of their physical make-up. There are various reasons for this, including environmental influences and interactions with other genes.

Explaining the connection between Epistasis and Incomplete Penetrance

Epistasis can explain incomplete penetrance by describing how the presence of one gene can mask or alter the expression of another gene. If a certain genotype is expected to display a certain phenotype, but this genotype's phenotype is masked by the presence or effect of another gene (the epistatic gene), then the individual might not exhibit the expected phenotype, resulting in incomplete penetrance.