Question

1. At the molecular level, what do you think causes variable expressivity? Answer in terms of protein function at a cellular or organ level.

2. At the molecular level, what causes gene dosage effect? Answer in terms of protein function at a cellular or organ level.

3. At the molecular level, what causes incomplete penetrance? Answer in terms of protein function at a cellular or organ level.

Answer 1

1.Although the features are highly variable, most people with this disorder have a mutation in the same gene (FBN1). As with reduced penetrance, variable expressivity is probably caused by a combination of genetic, environmental, and lifestyle factors, most of which have not been identified.

2.Gene dosage is the number of copies of a particular gene present in a genome.Gene dosage is known to be related to the amount of gene product the cell is able to express, however, amount of gene product produced in a cell is more commonly dependent on regulation of gene expression.Nonetheless, changes in gene dosage (copy number variations) due to gene insertions or deletions can have significant phenotypic consequences.

3.Incomplete penetrance may be due to the effect of the type of mutation. Some mutations of a given disease may exhibit complete penetrance, where as others in the same gene show incomplete or very low penetrance and Reduced penetrance in some genetic disorders may also depend on genetic background of gene carriers.