Review Question - QID 2823

Achondroplasia results from a mutation in fibroblast growth factor receptor-3.

Achondroplasia, the most common skeletal dysplasia, is caused by a mutation of fibroblast growth factor receptor-3. This disorder is characterized by frontal bossing, midface hypoplasia, otolaryngeal system dysfunction, and rhizomelic short stature. Orthopaedic manifestations are exhibited in the spine and the extremities.

Shirley et al discuss different orthopaedic manifestations of achondroplasia and their treatment. They report thoracolumbar kyphosis is seen in most infants, but typically it resolves when the child begins to walk. Anatomic anomalies of the vertebral column place the patient at risk for spinal stenosis as early as the first decade and especially during adulthood.

Illustration A shows characteristic findings of the vertebral body. Notice the short pedicles, which often leads to spinal stenosis in these patients.

Incorrect Answers:
Answer 1. Marfan syndrome is caused by a mutation in the fibrillin gene.
Answer 2. Gaucher's disease results from a mutation in glucocerebrosidase.
Answer 3. Fibrous dysplasia results from a GNAS activation mutation which leads to increased production of cAMP.
Answer 5. Diastrophic dysplasia most commonly results from a mutation in the SLC26A2 gene which affects a sulfate transporter.