What are the genetic characteristics of achondroplasia?

Achondroplasia is recognized as an autosomal dominant condition, meaning that only one copy of the mutated gene is necessary for a person to exhibit the characteristics associated with the disorder. Genetic studies have shown that it arises most frequently due to a specific mutation in the FGFR3 gene, which is responsible for regulating bone growth.

The fact that approximately 70% of achondroplasia cases are sporadic indicates that they occur from new mutations in the affected individual's genes, rather than being inherited from a parent who is affected. This mutational occurrence is typically due to errors in the formation of sperm or egg cells during meiosis.

In this context, identifying nachondroplasia as an autosomal dominant trait, characterized by a majority of cases arising sporadically, helps clarify its transmission dynamics and risk factors for affected individuals and their potential offspring, distinguishing it from conditions that follow different inheritance patterns.

The other answer choices describe features of other genetic ratios or inheritance patterns that do not align with the established understanding of achondroplasia.