Question
Cystic fibrosis disorder is:
| A. |
Autosomal dominant |
| B. |
Autosomal recessive |
| C. |
X-linked dominant |
| D. |
X-linked recessive |
Show Answer
|
Correct Answer � B Explanation |
 |
Genetics of Cystic Fibrosis (CF):
- Cystic fibrosis is caused by mutations in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene located on chromosome 7.
- It follows an autosomal recessiveinheritance pattern:
- Affected individuals inherit two defective CFTR alleles (one from each parent).
- Carriers (heterozygous individuals) have one defective allele but are asymptomatic.
Inheritance Patterns:
-
Autosomal Recessive:
- Both parents must carry the defective gene for the child to be affected.
- CF is the most common autosomal recessive disorder in Caucasian populations.
- Autosomal Dominant:
-
- Disorders with this inheritance require only one defective allele for the disease to manifest. Examples: Marfan syndrome, Huntington’s disease.
- Incorrect for CF.
- X-linked Dominant:
- Disorders occur when a mutation on the X chromosome is dominant. Examples: Rett syndrome.
- Incorrect for CF.
-
X-linked Recessive:
- Disorders primarily affect males because they have only one X chromosome. Examples: Hemophilia A, Duchenne muscular dystrophy.
- Incorrect for CF.
