Final answer:
Yes, repeat expansions are seen in maternal transmission of Huntington's Disease (HD). These trinucleotide repeat expansions can be passed from both mothers and fathers, although the effect known as anticipation is more often associated with paternal transmission. The correct option is A.
Step-by-step explanation:
Are repeat expansions seen in maternal transmission of Huntington's Disease (HD)? The answer is Yes. Huntington's disease is an example of a genetic disorder that can be caused by a phenomenon known as a trinucleotide repeat expansion.
This expansion, where a series of DNA bases is repeated more than normal, can increase in length when passed from parent to child, and the likelihood of expansion can vary depending on which parent transmits the affected allele.
In the case of HD, repeat expansions can indeed occur during maternal transmission, although the phenomenon of anticipation, where symptoms become more severe or occur at an earlier age in successive generations, is often more associated with paternal transmission. However, expansions can still happen regardless of whether the mother or the father passes on the mutated gene.