A child is diagnosed with cystic fibrosis. History reveals that ...

[jlmhmf]

A child is diagnosed with cystic fibrosis. History reveals that the child's parents are siblings. Cystic fibrosis was most likely the result of:
 
  a. X-inactivation.
  b. genomic imprinting.
  c. consanguinity.
  d. obligate carriers.

Question 2

Cystic fibrosis is caused by what gene abnormality?
 
  a. X-linked dominant
  b. X-linked recessive
  c. Autosomal dominant
  d. Autosomal recessive

[vboyd24]

Answer to Question 1

ANS: C
Consanguinity refers to the mating of two related individuals, and the offspring of such matings are said to be inbred. Consanguineous matings produce a significant increase in recessive disor-ders and are seen most often in pedigrees for rare recessive disorders. X-inactivation occurs when one X chromosome in the somatic cells of females is permanently inactivated. Genomic imprint-ing is related to methylation and other changes. Obligate carriers are those who have an affected parent and affected children and, therefore, must themselves carry the mutation.

Answer to Question 2

ANS: D
Cystic fibrosis is an autosomal recessive disorder. It is not a result of X links or dominant pa-thology.

[jlmhmf]

TYSM

[Liddy]

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