Answer discussion with at least 200 words and references
Discussion 1
Molecular bases of penetrance and expressivity
Mendel was performing his classical experiments with pea planta that have very clear-cut phenotypes. The plant was either with purple or white flowers, with yellow or green seeds, etc. However, when working with human disorders time to time we would observe certain traits that should be expressed but they are not, or they will be expressed but with varying degrees among the offspring [1, 2]. The advancement of the Molecular Genetics allowed for better understanding of the mechanisms underlying these phenomena [3].
Can you find examples of traits that show penetrance or varying expressivity not only in humans but in other organisms as well? Can you find explanation from a molecular point of view what the underlying mechanism is?
1. Griffiths AJF, Miller JH, Suzuki DT, et al. An Introduction to Genetic Analysis. 7th edition, New York: W. H. Freeman; 2000.
2. Miko, I. (2008) Phenotype variability: penetrance and expressivity. Nature Education 1(1):137
3. Zlotogora, J. Penetrance and expressivity in the molecular age. Genet Med 5, 347–352 (2003).
How to Solve Answer discussion with at least 200 words and references Discussion 1 Molecular bases of penetrance and expressivity Mendel was performing his classical experiments with pea planta that have very Nursing Assignment Help
Introduction: Penetrance and expressivity are two important concepts in genetics that describe the manifestation of a particular trait or genetic disorder. Penetrance refers to the proportion of individuals with a specific genotype who actually show the associated phenotype. On the other hand, expressivity refers to the degree or variability in the expression of a trait among individuals with the same genotype. Understanding the molecular bases of penetrance and expressivity has been made possible with advancements in molecular genetics.
Answer: Both penetrance and expressivity can be observed not only in humans but also in other organisms. One example of penetrance is seen in the genetic disorder neurofibromatosis type 1 (NF1). NF1 is caused by mutations in the NF1 gene, and individuals with this genotype can have varying degrees of symptoms. While some individuals may develop multiple neurofibromas and other characteristic features, others may have a milder presentation with only a few neurofibromas or even be asymptomatic. The underlying molecular mechanism for this varying penetrance in NF1 is not yet fully understood, but it is thought to involve the influence of modifier genes and environmental factors.
Expressivity can also be observed in various traits across species. For example, in a genetic disorder called Marfan syndrome, which affects the connective tissue, individuals may exhibit a wide range of symptoms and severity. Some individuals may have skeletal abnormalities, cardiovascular problems, and other systemic manifestations, while others may only have mild skeletal features. The molecular mechanism underlying the expressivity of Marfan syndrome is associated with the specific types and locations of mutations in the FBN1 gene, as well as other genetic and environmental factors.
From a molecular point of view, the underlying mechanism of penetrance and expressivity can involve various factors. These include genetic background, epigenetic modifications, interactions with other genes or modifier genes, and environmental factors. For penetrance, the presence of specific modifier genes or interactions with other genetic variants can affect the expression of the phenotype. For expressivity, differences in the type or location of mutations in the disease-causing gene, as well as dosage effects, can contribute to the variability in the phenotype.
In conclusion, penetrance and expressivity are observed in various traits and genetic disorders in both humans and other organisms. The molecular bases of these phenomena involve a complex interplay of genetic and environmental factors. Further research is needed to fully understand the underlying mechanisms and to provide more precise explanations for the variability in penetrance and expressivity across different traits and disorders.
