= autosomal recessive inheritance

Cause: mutation in gene-encoding sclerostin on chromosome 17q12-q21 leading to osteoblast hyperactivity

Age: manifestation in infancy

• early cranial nerve paralysis
• increased intracranial pressure (in 80%)
• massive square prognathic chin
• frontal bossing
• sclerosis of calvaria
• Hand
  • radial deviation
  • syndactyly

Cx: sudden death ← increase in intracranial pressure ← impaction of brain stem in narrowed foramen

DDx: Van Buchem disease