Which statement regarding inheritance of an autosomal-dominant gene allele with known variability in expressivity is true?
A)A person with low expressivity of the trait has a higher probability of having a child who does not express the trait at all.
B)A person with high expressivity of the trait has a greater risk of having a child who expresses the trait to an even greater degree.
C)The degree of expressivity of a given autosomal-dominant trait with known variability cannot be predicted by analyzing parental expression.
D)The degree of expressivity of a given autosomal-dominant trait with known variability is greater when the transmitting parent is the same sex as the child.

Question

Quizplus · Accepted Answer

When an autosomal-dominant gene with variable expressivity is inherited, the gene is always expressed, but some people have more severe problems than do other people. For example, the gene mutation for one form of neurofibromatosis (NF1) is dominant. Some people with this gene mutation express it as only a few areas of light-brown skin tone known as café au lait spots. Other people, even within the same family, who have the same gene mutation develop hundreds of tumors (neurofibromas) that protrude through the skin. A person with low expression of this problem can transmit the gene to his or her child, who then may have high expression of the problem. The reverse also is true. A person with high expression can transmit the gene to his or her child, who then may have low expression of the problem. Thus, the degree of expressivity of the trait in the transmitting parent does not predict the degree of trait expressivity in the inheriting child.

Which Statement Regarding Inheritance of an Autosomal-Dominant Gene Allele with Known