Achondroplasia Achondroplasia is an autosomal dominant disorder, however homozygous dominant individuals do not have achondroplasia - they either die before birth or very shortly thereafter. The homozygous recessive condition is normal. A dwarf couple decide to have children. Use this information to answer the following question(s). In the example above, what is probability that the couple will have a child with achondroplasia?

Question

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Since both parents have achondroplasia, they are heterozygous (Aa). The possible genotypes for their children are AA, Aa, and aa. AA results in death, Aa results in achondroplasia, and aa is normal. The probability of a child having achondroplasia (Aa) is 2 out of the 3 viable outcomes (Aa, Aa, aa), which is 2/3.

Achondroplasia Achondroplasia Is an Autosomal Dominant Disorder, However Homozygous Dominant