Achondroplasia; the most common type of human dwarfism, affects 1 in 15,000 to 1 in 40,000 individuals. Many cases of achondroplasia are the result of a spontaneous mutation. After the mutation occurs, however; it becomes an autosomal dominant trait.Two individuals with achondroplasia had a son of average height and two other sons and a daughter with achondroplasia. Which of the following statements do not explain how the parents can have a child of "average" heightThe "average" height child is

What is dwarfism and what causes the growth defect?