Complex genetic disorder affecting the bone, skin and endocrine systems

Aetiology

• Post-zygotic somatic GNAS mutation (not germline) resulting in mosaicism
• Results in constitutive adenylyl cyclase signalling and overproduction of several hormones

Clinical features

• Cafe-au-lait skin pigmentation
• Polyostotic fibrous dysplasia
• Precocious puberty (typically females)
• Thyroid nodules
• GH excess
• Cushing's syndrome