Clinical Manifestations. Clinical findings vary widely. Formerly, patients with similar but less severe signs were thought to have a variant form or a different condition. The differences, more apparent than real, were due to variable phenotypic expression.

A unique group of malformations is evident at birth, with additional characteristics appearing later. In the newborn period, the head appears normal, but many patients develop a characteristic facial appearance with a narrow root and broad midportion of the nose, long and broad lip philtrum, and square jaw. The prominent area around the mouth, coupled with the other characteristic facial features, gave rise to the now obsolete term cherub dwarf. The face is long and full with a high, broad forehead. Capillary hemangiomas are common in the midforehead but fade or disappear with age. Abnormalities of the palate are seen in 50% of patients and include complete, partial, or submucous clefts, bifid uvula, or double uvula with a median longitudinal ridge. These palatal abnormalities—and possibly laryngeal defects—produce the characteristic soft rasping or hoarse voice.

In 80% of patients, the ears swell in the first few days or weeks after birth, giving the appearance of acute inflammation. The swelling subsides spontaneously in 4 to 6 weeks, resulting in a cauliflower ear. Calcification and ossification occur later. Hearing is not affected by the small size of the external auditory canals but can be impaired by deformity of the middle ear ossicles.

Reduced height is primarily due to rhizomelic shortening of the limbs and is further augmented by flexion contractures of the joints, especially the hips and knees. Adult height ranges from 34 to 48 inches.

Partial and complete joint dislocation is also common, particularly in the shoulders, elbows, hips, and patellae. The dysplastic hip changes, coxa vara, and hip dislocation combine to produce a grossly abnormal gait.

Hand malformation is a hallmark of diastrophic dwarfism. The hypermobile thumb and deformed first metacarpal create an abducted hitchhiker position. The fingers are short and broad with ulnar deviation; there is limitation of movement due to ankyloses of the proximal interphalangeal joints (symphalangism). Severe progressive clubfoot is another characteristic.

The trunk is deformed by excessive lumbar lordosis that develops early in life. Scoliosis, which may also begin in infancy, becomes more severe with weight bearing and leads to trunk deformity and barrel chest. Kyphosis of a variable degree accompanies the scoliosis, and the resultant deformity further reduces height. Spinal changes, especially cervical kyphosis, may cause catastrophic neurologic problems.

Radiographic Findings. Characteristic signs are short, broad, long bones with flared metaphyses. Development of the epiphyses is delayed and irregular, and stippling has been observed. The epiphyses of the proximal femurs, absent at birth, are flat and distorted when ossification does occur. The epiphyses of the proximal tibias tend to be triangular and larger than those of the distal femurs. Other findings include cervical kyphosis and dysplasia; thoracolumbar kyphoscoliosis; partial or complete dislocation of the hips; precocious ossification of the costal cartilage; small, oval, or triangular first metacarpals; irregular deformity of the metacarpals, metatarsals, and phalanges; and clubfoot.