Achondroplasia is a form of dwarfism in humans. It is caused by a mutant allele of the fibroblast growth factor receptor gene (FGFR) that produces an overactive protein. Having one copy of the mutant allele results in dwarfism. Two copies of the mutant allele results in death before birth.
-If two people with achondroplasia have a child together, what is the probability that their child will also have achondroplasia?
A)0
B)1/2
C)2/3
D)3/4
E)1

Question

Quizplus · Accepted Answer

Achondroplasia is inherited in an autosomal dominant manner. Each parent has one copy of the mutant allele (A) and one normal allele (a), making their genotype Aa. When they have a child, the possible genotypes are AA (lethal), Aa (achondroplasia), and aa (normal height). Since AA results in death before birth, only Aa and aa are viable, making the probability of a child having achondroplasia (Aa) 2 out of 3 viable outcomes.

Achondroplasia Is a Form of Dwarfism in Humans