What is the probability that the son will be a carrier of the recessive allele?
Ectrodactyly (lobster claw) is an inherited physical defect in humans occurring in homozygous recessive individuals. If 2 normal parents had a daughter affected with this condition and a normal son...
Ectrodactyly (lobster claw) is an inherited physical defect in humans occurring in homozygous recessive individuals. If 2 normal parents had a daughter affected with this condition and a normal son...
1 Answer
Explanation:
First we have to know the genotype of the parents. Lets call the dominant allele for ectrodactyly
The disease is homozygous recessive, so the daughter must have two recessive alleles, her genotype is
Knowing this we can make a cross table to show all possible genotypes of the first generation offspring:
Since we know that the son is not affected, he is either homozygous dominant (
In this case we are interested in the chance that he is a carrier, which is the case when he is heterozygous. As seen above, this chance is 2 out of 3, which is