precocious puberty

McCune-Albright Syndrome

Clinical Characteristics
Ocular Features: 

This disorder is of interest to ophthalmologists because compression of the optic nerve can occur from fibrous dysplasia of the canal.  However, this occurs only in some cases.  The risk of optic neuropathy is higher in patients with elevated levels of growth hormone.

Systemic Features: 

This disorder is clinically heterogeneous because of the variable degree of involvement of all bony tissue.  The primary manifestations are secondary to endocrine dysfunction and fibrous dysplasia.  Thyrotoxicosis, Cushing syndrome, pituitary gigantism, hearing deficits, and precocious puberty (in both sexes) are common.  The skin often has a cafe-au-lait pattern of pigmentation.


Postzygotic activating mutations in the GNAS gene on chromosome 20 (20q13.2) are likely responsible for this disorder although too few familial cases have been reported to document a mode of inheritance.  It has been suggested that an autosomal dominant lethal gene is involved with survival only in the presence of significant mosaicism.

Treatment Options: 

Recent evidence suggests that early treatment (before age 18 years) in patients with elevated growth hormone levels using pharmacologic intervention, surgery, and/or radiotherapy is associated with less optic neuropathy compared with patients who are treated later.  The impact on hearing impairment is less certain and awaits further studies.

Not all patients have significant optic nerve compression. Decompression of the optic nerve canal is beneficial in about half of cases in which significant nerve encasement is present but should be performed only when progressive optic neuropathy occurs, especially when growth hormone levels are elevated.

Article Title: 

McCune-Albright syndrome

Dumitrescu CE, Collins MT. McCune-Albright syndrome. Orphanet J Rare Dis. 2008 May 19;3:12.

PubMed ID: 
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