What is the genetic inheritance pattern of achondroplasia?

Achondroplasia is a genetic disorder characterized by an abnormality in bone growth, leading to dwarfism. It follows a genetic inheritance pattern of a single dominant allele. This means that only one copy of the mutated gene (FGFR3) is sufficient to cause the condition. If a person inherits the mutated allele from one parent, they will manifest the traits associated with achondroplasia.

The dominant nature of the allele is crucial in understanding how the disorder is transmitted. Individuals with one affected parent have a 50% chance of inheriting the gene and therefore the condition. In contrast, if the inheritance pattern were autosomal recessive, both copies of the gene would need to be mutated for the individual to express the disorder, which is not the case with achondroplasia.

X-linked dominant inheritance involves genes located on the X chromosome and typically affects males and females differently, particularly in terms of severity, which does not apply to achondroplasia as it occurs on an autosome. Lastly, polygenic inheritance refers to traits controlled by multiple genes, which does not align with the singular dominant nature of the allele responsible for achondroplasia.

The clarity of this inheritance pattern is essential for genetic counseling and understanding the risk of transmission to offspring.