Difference between penetrance and expressivity?

Question: Difference between penetrance and expressivity?

Penetrance and expressivity are two concepts used in genetics to describe the variation in the presentation of inherited traits.

Penetrance refers to the proportion of individuals carrying a specific genetic mutation who actually display the associated trait or phenotype. It represents the likelihood or probability of a particular genotype manifesting as a phenotype. High penetrance means that a large majority of individuals with the mutation will exhibit the trait, while low penetrance indicates that only a fraction of individuals will show the trait.

Expressivity, on the other hand, describes the degree or intensity of the phenotype in individuals who carry the same genetic mutation. It measures the variation in the manifestation of the trait among individuals with the same genotype. Expressivity can range from mild to severe, with individuals displaying varying degrees of symptoms or characteristics associated with the mutation.

In summary, penetrance focuses on the presence or absence of a trait in individuals with a specific genetic mutation, while expressivity describes the variation in the degree or intensity of the trait among individuals with the same mutation.