Question

What does it mean when something has a low penetrance but a high expressivity?

Answer 1

When a trait has low penetrance, it means not everyone with the gene will exhibit the trait, but those who do show a strong manifestation of it (high expressivity).

Step-by-step explanation:

When something has a low penetrance but a high expressivity, it means that the trait associated with the gene may not always be expressed in individuals who have the gene (low penetrance), but when it is expressed, it is expressed to a high degree (high expressivity).

For example, let's consider a genetic condition called polydactyly, which is having extra fingers or toes. If a person has the gene for polydactyly, they may not actually have extra fingers or toes (low penetrance), but if the trait is expressed, they may have multiple extra digits (high expressivity).

In summary, low penetrance means that not everyone who has the gene will exhibit the trait, while high expressivity means that those who do exhibit the trait will show a strong manifestation of it.

Answer 2

Low penetrance indicates that not everyone with the gene expresses the trait, while high expressivity means that those who do express it show varied and prominent features.

Step-by-step explanation:

Penetrance refers to the percentage of individuals with a particular genotype who exhibit the expected phenotype. When a trait has low penetrance, it implies that a significant proportion of individuals carrying the responsible gene may not manifest the associated trait, leading to a variable expression of the phenotype. This variability can be influenced by environmental factors, genetic modifiers, or other complex interactions within the organism.

Expressivity, on the other hand, relates to the degree of variation in the phenotype among individuals who have the same genotype. High expressivity suggests that when the trait is expressed, it can manifest with diverse and noticeable features. In the context of low penetrance and high expressivity, even though not all individuals with the gene exhibit the trait, those who do express it may display a wide range of observable characteristics or symptoms associated with the trait.

In summary, low penetrance and high expressivity characterize a genetic scenario where the presence of a particular gene may not consistently result in the manifestation of a trait across individuals, but when the trait is expressed, the observable features are distinctive and variable. This phenomenon underscores the complex interplay between genetic and environmental factors in determining the phenotypic outcomes of specific genetic traits.