If both parents have a normal phenotype but are heterozygous for the cystic fibrosis gene, what is the chance that they could have a child with cystic fibrosis?
-
This is a recessive autosomal disease.
if you think that allele for cystic fibrosis as f, and normal is F,
then both parents would be Ff.
Do a punnet square with Ff x Ff and it will show that the child would have a 25% chance of being ff (cystic fibrosis) and 50% chance for just being a carrier (Ff), and 25% for FF (not a carrier)
if you think that allele for cystic fibrosis as f, and normal is F,
then both parents would be Ff.
Do a punnet square with Ff x Ff and it will show that the child would have a 25% chance of being ff (cystic fibrosis) and 50% chance for just being a carrier (Ff), and 25% for FF (not a carrier)