Is The Allele For Cystic Fibrosis Dominant Or Recessive?


3 Answers

Anonymous Profile
Anonymous answered
Recessive because 2 of these alleles must be present to produce a child with cystic fibrosis. When only 1 parent is a cf carrier that allele wont be passed on because the dominant allele will be prominent. If 1 parent is a suffer of cf then all offspring will be a cf carrier and have the cf recessive allele. But when 2 parents with this allele have children then the chances of there child having cf increases to a 1 in 4 chance.
thanked the writer.
aileeny commented
Alicia, To quote you, " when only 1 parent is a CF carrier that allele wont be passed on because the dominant allele will be prominant". This is incorrect. It is a 50/50 chance each time ,whether this carrier parent passes on the mutated cf allele or the normal cf allele. So it IS passed on but the offspring will be a carrier like the 1 carrier parent as it will have received the normal dominant "cf" allele from the other normal parent. But just 1 carrier parent cannot produce a cf child.
aileeny Profile
aileeny answered
The allele for CF is recessive, which means that the child has to inherit a CF gene from both parents who are carriers and have no idea of their mutation.     Interestingly when two first cousins marry their children have 8 times more chance of being a CF sufferer than if either parent had out married. This is because the same shared grandparent of the cousins could be a possible  carrier and has handed it down to both his/her grandchild.

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