11. In college, you loved your genetics class and decided to be a Genetic Counse

Question

11. In college, you loved your genetics class and decided to be a Genetic Counselor. Nichole is a young woman in her 20s. She wants to know the probability that she would have a child with a genetic disorder caused by a trisomy How would you advise Nichole? Give an example of a common genetic disorder caused by a trisomy and how you could detect it. 3 pts) a. Nichole has an older sister named Mary, who is 45 years old. Mary wants to have children. How would you advise Mary about the risks of having a child with a genetic disorder caused by a trisomy? (3 pts) b.

Explanation / Answer

Please find the answers below:

Answer a: Trisomy is a genetic condition in which one of the gametes contains an extra chromosome either in the set of the autosomes or the sex-chromosomes. Under such conditions, the gamete is not able to function properly and hence the individual develops irreversible genetic disorder. This type of genetic condition arises due to failure of non-disjunctioning of the chromosomes during meiotic division.

For example, trisome of the 21st pair of chromosome causes Down's syndrome in humans.

For the present case, the probability of having a trisomic child can be understood by the fact that meiosis takes place in the diploid cells to give rise to haploid cell. One set of meiosis gives rise to 4 haploid gametes. Now, non-disjunctioning mediated trisomy may arise in any of these daughter cells or gametes. Thus, there is 1/4 or 25% chances for each individual to bear a trisomic child.

Answer b: The risk of trisomic child increases when the conceiving mother has higher age, i.e. more than 35 years. This is because the efficiency of meiosis decreases with age and hence the chances of faulty meiosis increase. Hence, it is advisable for Mary to undergo karyotyping of her gametes or to perform amniocentesis during the early phase of her pregnancy to detect any possible trisomy.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.