If Your Dad Has a 1 Dominant Gene and 1 Recessive Gene for Cystic Fibrosis and Your Mom Has 2 Recessive Genes?
Thursday, September 9th, 2010 at
5:17 pm
pinkinmv asked:
for cystic fibrosis will your children have cystic fibrosis, and what is the percentage that they will?
Tagged with: Dad • Dominant Gene • Mom
Filed under: Cystic Fibrosis
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u only get cystic fibrosis if both ur mom AND dad have genes
Let’s say that the letter for cystic fibrosis is “C” for dominant and “c” for recessive. That means that you could have the genes:
Cc
cc
If you had Cc, you’d have cystic fibrosis. cc= you don’t have cystic fibrosis. Now, if you hade the genes “Cc”, your children could get anything… it depends on your spouse’s alleles. Tell me what your spouse’s alleles are, then I’ll be happy to edit and give you a precise answer, but I believe that the chance is about 33.33% that your children WILL have cystic fibrosis.
You get cystic fibrosis if you inherit a dominant allele from either parent, mom OR dad, not both.
Happy Potter fanatic above me is correct (:
lOl..
The answer of 33% is incorrect.
Cystic fibrosis is an autosomal recessive disease, meaning that to develop the disease, you need 2 copies of the recessive CF gene.
If we label the dominant gene (normal one) as C, and the recessive gene (CF gene) as c, we can represent the father as: Cc, and the mother as cc (she has the disease).
If they have children, there are two possible outcomes. The mother can only pass the recessive c gene. If the father passes the dominant C gene, their child will be Cc – a carrier. If he passes the recessive c gene, then their child will be cc – sick with CF. Since the father has a 50/50 chance for passing the c gene (and the mom has a 100% chance of passing the c gene), their child has a 50% chance of having CF.
Here’s a Punnett square illustration:
________C_____c___Father
c. . . . . . Cc . . . cc
c. . . . . . Cc . . . cc
Mother . . 50% . .50%