The typical facies has prominent eyebrows and ear
lobes and a broad, flat nose with a flat nasal bridge. The forehead is
usually quite prominent. The face showed a V-shaped configuration with
midface hypoplasia, straightening of the gonial angle (the angle between the
ramus and the body of the mandible), flattening of the malar eminences,
hypoplastic zygomatic bones, and abnormally pointed chin. The opening of the
gonial angle leads to overclosure of the mandible with functional
prognathism. Alveolar and sutural bone growth in the face is decreased and
associated with partial dental agenesis. Craniosynostosis can occur. Skull
radiographs show a striking thinning of the calvaria and brachycephaly. The
morphology of the cervical vertebrae may be abnormal, and some degree of
thoracic scoliosis seems to be common. The lumbosacral spine, however, was
described as normal. Cortical thickening of the bone appears to be a
prominent feature, most commonly found in the long bones, which can result
in encroachment of the medullary cavity. The ribs and the superior pubic
ramus are often thin. Minor changes were found in the bones of clavicles,
hand, and feet. In one of the patients, thinning of the mandible led to
recurrent mandibular fractures (only in one case with a trauma appropriate
enough to explain the fracture). All patients in the initially described
family were hyperuricemic but not hyperuricosuric, and no other metabolic
abnormalities could be detected. However, increased erythrocyte
sedimentation rate (30-40 mm/hour) and C3 complement levels have been
reported. The plasma fibrinogen level was low in all family members.
Diastolic hypertension was present in three of the four initially described
patients. The patients are mentally normal.