Nokea
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.
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The parents of a child with brachydactyly ask if their next child will also be affected. Which of the following is the basis for the nurses' response related to autosomal dominant 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: C
Rationale: Brachydactyly is an autosomal dominant disorder, meaning that there is a 50% chance that offspring will be affected. It happens equally in males and females.
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.
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.
When taking a family history in the genetic clinic, the nurse will ask information about how many generations in the past?
- A. 2
- B. 3
- C. 4
- D. 5
Correct Answer: B
Rationale: A detailed three-generation family history, or pedigree, offers great insight into possible genetic conditions within a family.
Which of the following terms describe the process by which the codon sequence is converted to amino acids?
- A. Transcription
- B. Mutation
- C. Translation
- D. Processing
Correct Answer: C
Rationale: After transcription is complete, translation occurs. Translation is the process through which the codon sequence is converted into amino acids.