Chapter 6 Case Study: Results Worry Pregnant Woman Martha Lawrence was nervous a

Question

Chapter 6 Case Study: Results Worry Pregnant Woman

Martha Lawrence was nervous about going to the human genetics unit at the hospital. Her physician referred her because she was unexpectedly pregnant at age 41 which predisposed her to be at risk for having a child with a chromosomal abnormality, especially Down syndrome. She was 18 weeks pregnant which would not leave much time if she wanted to terminate the pregnancy since it takes 7-14 days for the results of an amniocentesis procedure. Woman older than age 35 have a much higher risk of having a child with a chromosomal abnormality than younger women.

Martha previously had two normal pregnancies and her children are now 13 and 17. The genetic counselor, Dr. Gould suggested that Martha have amniocentesis (removal of fluid and cells around the fetus) to examine fetal chromosomes.

In discussing the results of the test, Dr. Gould said the fetus did not have an extra copy of chromosome 21 and thus did not have Down syndrome. However analysis showed the presence of an extra Y chromosome (XYY instead of XY), a condition called Jacob syndrome. This condition is fairly common in the United States, five of ten boys are born with an XYY set of chromosomes.

1. Read up on the XYY condition. Based on the karyotype that Dr. Gould obtained by amniocentesis, list five options available to Martha.

2. Which do you think is the best option in this situation?

3. Knowing what you do about the different aneuploidy conditions, fi the diagnosis were Down syndrome, would your decision change? Why or why not?

4. Keeping in mind that Martha was primarily concerned about her age and the chances of having a child with trisomy 21, should Dr. Gould tell her about the abnormal XYY karyotype? Why or why not?

5. Dr. Gould considered telling Martha’s husband about the test results before she told Martha. Should she have? Why?

Explanation / Answer

2. Looking at the various aneuploidy conditions and comparing them with the Jacob syndrome, it could be suggested that Martha can keep the child who is about to be born.

3. This option is possible because unlike other aneuploidies, Males with an extra Y chromosome do not show a significant mental retardation or physical disabilities or neither are they phenotypically different. The only difference is that they have slight developmental abnormalities such as increased height and slight lower IQ, but comparable to an average human. If the child was diagnosed with a Down syndrome, then the option to abort the child could be provided to Martha because of the abnormalities that a child possesses due to the syndrome.

4. No, it is not very important to tell Martha about the trisomy because she thought at this point of time before explaining the same to her husband. The reason for this is Martha's though that the trisomy has occurred due to age , but Jacob syndrome is not due to age but a random event.

5. Yes, it would have been wise to tell the husband and explain it to him before telling to Martha as he would be able to understand the situation without any ore conceived notions.

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