Nokea
A newly pregnant woman asks the nurse what the best time is for chorionic villus sampling? Which of the following time frames is the basis for the nurse's response?
- A. 8-10 weeks
- B. 11-12 weeks
- C. 15-16 weeks
- D. 19-20 weeks
Correct Answer: B
Rationale: Chorionic villus sampling (CVS) is done in the first trimester, usually between 11 and 12 weeks gestation.
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The nurse is counselling a couple in which the man has an autosomal recessive disorder, and the woman has no gene for the disorder. The nurse uses Punnett squares to show the couple that the probability of their having a child with the disorder is which of the following percentages?
- A. 0%
- B. 25%
- C. 50%
- D. 75%
Correct Answer: A
Rationale: When one parent has no gene for an autosomal recessive disorder, the children will not display the characteristics of the disorder. However, the children will be carriers of the autosomal recessive disorder.
When carrying out pre-symptomatic testing, which of the following diseases has a gene that is 100% penetrant?
- A. Tay-Sachs disease
- B. Fragile X syndrome
- C. Cystic fibrosis
- D. Huntington's disease
Correct Answer: D
Rationale: In pre-symptomatic testing, an individual has genetic testing to determine whether she or he carries a genetic mutation for a genetic disorder. Typically, individuals electing this testing are members of a family that exhibits a genetic disorder. An example of this would be genetic testing for Huntington's disease, an adult-onset condition characterized by progressive neurological degeneration. The gene responsible for Huntington's disease is 100% penetrant, that is, everyone who inherits this mutation will exhibit the disease and, since there is no cure, will die of the disease.
The parents of a child with cystic fibrosis ask if their next child will also be affected. Which of the following is the basis for the nurse's response related to autosomal recessive disorders?
- A. There is a 25% chance that the child will be affected.
- B. All male offspring are affected.
- C. There is a 50% chance that the child will be affected.
- D. All female offspring will be affected.
Correct Answer: A
Rationale: Cystic fibrosis is an autosomal recessive disorder, meaning that there is a 25% chance that offspring will be affected. It happens equally in males and females.
A patient whose mother has diagnosed with BRCA gene-related breast cancer asks the nurse, 'Do you think I should be tested for the gene?' Which of the following responses by the nurse is most appropriate?
- A. In most cases, breast cancer is not caused by the BRCA gene.
- B. It depends on how you will feel if the test is positive for the BRCA gene.
- C. There are many things to consider before deciding to have genetic testing.
- D. You should decide first whether you are willing to have a double mastectomy.
Correct Answer: C
Rationale: Although presymptomatic testing for genetic disorders allows patients to take action (such as mastectomy) to prevent the development of some genetically caused disorders, patients also need to consider that test results in their medical file may impact other areas of their life. Telling a patient that a decision about mastectomy should be made before testing implies that the nurse has made a judgment about what the patient should do if the test is positive. Although the patient may need to think about her reaction if the test is positive, other issues also should be considered. Although most breast cancers are not related to BRCA gene alterations, the patient with the gene alteration has a markedly increased risk for breast cancer.
A male with mild hemophilia asks the nurse, 'Will my children have hemophilia?' Which of the following responses by the nurse is most appropriate?
- A. All of your children will be at risk for hemophilia.
- B. Hemophilia is a multifactorial inherited condition.
- C. Only your male children are at risk for hemophilia.
- D. Your female children will be carriers for hemophilia.
Correct Answer: D
Rationale: Because hemophilia is caused by a mutation of the X-chromosome, all female children of a man with hemophilia are carriers of the disorder and can transmit the mutated gene to their offspring. Sons of a man with hemophilia will not have the disorder. Hemophilia is caused by a genetic mutation and is not a multifactorial inherited condition.