The mode of inheritance is autosomal, which means that it does not involve the x or y chromosomes, which determine sex. It is also recessive, which means that the disease is inherited from both parents. About five percent of Caucasian Americans (one in 28) are believed to carry the gene. Carriers do not have symptoms of the disease, and often do not even realize that they are one of more than 10 million people who carry cystic fibrosis. The number of cystic fibrosis carriers is likely to increase in the future.
This chart can help you determine the genetic probability of having a child with cystic fibrosis
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Parents
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Chance of Unaffected Child
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Chance of Child Carrier
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Chance of Child with CF
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Unaffected + Carrier
|
50%
|
50%
|
No Chance
|
|
Two Carriers
|
25%
|
50%
|
25%
|
|
Unaffected + CF Patient
|
No Chance
|
100%
|
No Chance
|
|
Carrier + CF Patient
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No Chance
|
50%
|
50%
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