Review Question - QID 8256

The patient shown has findings consistent with pseudoachondroplasia, which is caused by a mutation in COMP.

Pseudoachondroplasia patients have short stature (3.5-4.5 feet) and resemble achondroplastic dwarfs with rhizomelic proximal segments. Limbs are disproportionately short, with limitation of elbow extension. Radiographically, patient appearance is normal at birth but become severely abnormal with growth. Pseudoachondroplasia is distinguished from achondroplasia by multiple joint deformities and normal facies.

Beals et al. report pseudoachondroplasia is characterized by short-limbed short stature with limb deformities, normal facies, and severe early dysplasia of the hips.

Figure A is a clinical photo that shows the rhizomelic proximal segments and multiple joint deformities characteristic of Pseudoachondroplasia. Figure B is a radiographs that shows severe early dysplasia of the hips.

Incorrect Answers:
Answer 1: FGFR3 mutation is found in achondroplasia and can be diagnosed at any age. Clinical features include short stature (adult height 4 feet), a long trunk, rhizomelic extremities, and dysmorphic facies (large head, frontal bossing, and depressed nasal bridge).
Answer 2: COL2A gene mutation is found in spondyloepiphyseal dysplasias (ie, Kniest syndrome, Stickler syndrome, spondyloepiphyseal dysplasia congenital). This condition is usually evident at birth: facies with mild midface flattening, short necks, and barrel-shaped chests. At walking age, thoracolumbar kyphosis with excessive lordosis is evident.
Answer 3: Mutation in CBFA1 is found in cleidocranial dysplasia presenting with hypo/aplasia of the clavicles, open skull sutures with bulging calvarium, midface hypoplasia, wide symphysis pubis, mild-to-moderate short stature, and short middle phalanx of the little finger.