An infant who is 4 days postpartum has been diagnosed with a ...

[TVarnum]

An infant who is 4 days postpartum has been diagnosed with a single-gene disorder. The parents of the child have a number of questions about the etiology of the health problem, which the physician is attempting to address in detail.
 
  Which of the following teaching points most accurately captures an aspect of single-gene congenital disorders?
  A)
  Affected genes are present on autosomal chromosomes rather than sex chromosomes.
  B)
  The majority of single-gene disorders manifest near the time of puberty.
  C)
  A particular defect can be caused by mutations at several different loci.
  D)
  Single-gene disorders are associated with existing rather than new mutations.

Question 2

How could a health care professional most accurately explain an aspect of the underlying structure of DNA to a colleague who is unfamiliar with genetics?
 
  A)
  DNA consists of nucleotides plus one of the four nitrogenous bases.
  B)
  In the base pairs, adenine combines with thymine and guanine with cytosine.
  C)
  Thymine and cytosine are considered the purine bases.
  D)
  The backbone of a DNA molecule consists of either deoxyribose or phosphoric acid.

[TINA]

Answer to Question 1

Ans:
C

Feedback:

A particular defect is not limited to any one specific locus. Single-gene disorders can be present on either autosomal or sex chromosomes, and they are primarily pediatric disorders. They can result from either existing or new mutations.

Answer to Question 2

Ans:
B

Feedback:

The base pairings of DNA are such that adenine combines with thymine and guanine with cytosine. DNA also includes the sugar deoxyribose, while thymine and cytosine are considered the pyrimidine bases. The backbone of DNA includes both deoxyribose and phosphoric acid.

[TVarnum]

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