Question

Achondroplasia is a form of dwarfism caused by a dominant allele. The homozygous dominant genotype causes prenatal death, so individuals who have this condition are all heterozygotes. In the questions below, show how you came to your answer.
a) If a person with achondroplasia mates with a person of average height who does not have achondroplasia, what percentage of their children would be expected to be of average height?
b) If two persons with achondroplasia have children, what percentage of their children would be expected to have achondroplasia?

Answer 1

Answer:

The correct answers are

Question a) "50%".

Question b) "66%".

Explanation:

Achondroplasia is caused by a dominant allele, which means that a person with a "A" allele will develop this condition. In this case, all the people with Achondroplasia are heterozygotes "Aa" because the dominant genotype "AA" causes prenatal death. If a person with achondroplasia "Aa" mates with a person of average height "aa", the expected percentage of children with average height will be 50%, since there are 50% of chances of having "aa" children and 50% chances of having "Aa" children. Also, If two persons with achondroplasia have children ("Aa" x "Aa") , the expected percentage of children with achondroplasia will be 66%. The probability of having children with the "Aa" genotype is 50%, however since the "AA" genotype causes prenatal death, this genotype is not considered in the percentage.