The disease involves mainly the head and neck
(brachycephaly, enlarged calvaria, frontal bossing with wide forehead and
hypertelorism, wormian bones, large foramen magnum, hypoplasia or absence of
frontal and paranasal sinuses, midfacial hypoplasia, micrognathia, nonunion
of mandibular symphysis, high arched palate or cleft palate, delayed
eruption of deciduous and permanent teeth, enamel and root hypoplasia,
cavities, supernumerary teeth [up to 30 extra teeth have been described],
and deafness) and the skeleton (short stature, spina bifida occulta,
[unilateral or bilateral] hypoplastic [more often at the acromial than at
the sternal end] or aplastic [rare] clavicles with the ability to appose the
shoulders, narrow, bell-shaped thorax with short, oblique ribs, cervical
ribs, small scapula with dysplastic acromial facets and supraspinatus
fossae, hypoplastic pubic bones with widened symphysis pubis, hip
dislocation, generalized joint laxity, brachydactyly, excessive length of
metacarpal and metatarsal II (and V) bones secondary to extra
epiphyses, short middle phalanx of the fifth fingers, cup-shaped and
hypoplastic distal phalanges with onychodysplasia). Respiratory distress
occurs frequently.