Achondroplasia

Achondroplasia is a genetic condition that affects the development of bones, primarily impacting the growth of the arms and legs. It is the most common cause of dwarfism and results from changes in the growth of cartilage into bone. This condition mainly involves the skeletal system, leading to shorter stature and distinctive facial features. People with achondroplasia often have a normal-sized torso but shorter limbs, especially the upper arms and thighs. The condition can also affect the spine and cause complications such as spinal stenosis. Despite these differences, most individuals with achondroplasia have normal intelligence and life expectancy.

Achondroplasia is a genetic disorder characterized by impaired endochondral ossification, leading to disproportionate short stature with rhizomelic limb shortening. It is caused by a gain-of-function mutation in the FGFR3 gene, which encodes the fibroblast growth factor receptor 3, resulting in constitutive activation that inhibits chondrocyte proliferation in the growth plate. This mutation is typically sporadic but can be inherited in an autosomal dominant pattern. Clinically, patients present with macrocephaly, frontal bossing, midface hypoplasia, and trident hands. The condition is significant due to its impact on skeletal growth and potential complications such as foramen magnum stenosis and obstructive sleep apnea. Radiographically, characteristic findings include shortened long bones with metaphyseal flaring and a narrowed interpedicular distance in the lumbar spine.