What is the most likely explanation for a baby boy to have Tay-Sachs disease when the child's mother is not a carrier for the problem, but the father is a carrier?
A)The mother is not really the biological parent of this child.
B)The mother's normal gene allele is not expressed, and the father's Tay-Sachs allele is expressed.
C)A new mutation occurred in the father's sperm in which the Tay-Sachs gene has become dominant.
D)The father's Tay-Sachs gene has been translocated from its usual locus to the Y chromosome and thus is expressed in any male child.

Question

Quizplus · Accepted Answer

It is possible for a specific gene from one parent to be silenced and not expressed even though the gene is normal through a variety of epigenetic events. Although the gene for Tay-Sachs is recessive, and usually two Tay-Sachs genes are required for expression of the disease, if a normal gene is not expressed, the other affected allele is expressed as if it were dominant.

What Is the Most Likely Explanation for a Baby Boy