Achondroplasia is classified under which type of inheritance?

• A. Autosomal Recessive
• B. Autosomal Dominant
• C. X-linked Recessive
• D. Y-linked

Answer: (B)

Achondroplasia is classified as an autosomal dominant inheritance pattern. This means that only one copy of the mutated gene is sufficient to cause the disorder. In the case of achondroplasia, the mutation typically occurs in the FGFR3 gene, which affects bone growth and development. Individuals who inherit this mutated gene from just one parent will express the characteristics of achondroplasia, making it a classic example of autosomal dominance.

In autosomal dominant conditions, the trait can be passed on to the offspring regardless of whether the second allele is normal, leading to a 50% chance of transmission to each child if one parent is affected. This differs from other inheritance patterns—autosomal recessive conditions, for example, require two copies of the mutated gene for the trait to manifest. In contrast, X-linked recessive disorders primarily affect males, as they have only one X chromosome, while females may be carriers if they have one normal and one mutated X chromosome. Y-linked inheritance only affects traits that are inherited through the Y chromosome, which is not applicable to achondroplasia. Hence, the classification of achondroplasia as autosomal dominant is accurate and aligns with the genetic principles governing this disorder.