What it is
McCune-Albright syndrome is a rare mosaic disorder caused by a GNAS gene change that arises after conception (post-zygotic), so it is present in only some of the body's cells and is not inherited or passed to children. It classically combines bone, skin, and hormone-gland features.
Signs and symptoms
Elevated circulating growth hormone concentration
Excess growth hormone can occur and is associated with severe fibrous dysplasia of the skull and face.
Hyperthyroidism
Several hormone glands can become overactive. Among reported features, an overactive thyroid (hyperthyroidism) is one of the endocrine problems that can occur.
Precocious puberty
Puberty can begin unusually early (precocious puberty), one of the three classic features.
Hyperparathyroidism
Among the associated endocrine problems, the parathyroid glands can become overactive (hyperparathyroidism).
Increased circulating cortisol level
Overactive endocrine glands can also raise cortisol (hypercortisolism), part of the wide range of hormone effects seen in this condition.
Polyostotic fibrous dysplasia
Fibrous dysplasia replaces normal bone with weaker fibrous tissue in several bones (polyostotic), which can cause deformity and fractures.
Bone pain
Bone pain is common where fibrous dysplasia is active and is a frequent reason people seek care.
Large cafe-au-lait macules with irregular margins
Flat, tan skin patches (café-au-lait macules), often with irregular borders, are one of the three hallmark features.
Pathologic fracture
Weakened bone can break with little or no injury (pathologic fracture), and may cause a limp or pain.
Treatment and management
What the research describes, not a recommendation. Treatment decisions belong with your clinician.
This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.
bisphosphonates
Bisphosphonates are commonly used to reduce bone pain in fibrous dysplasia. The research describes them as effective for pain, while limiting the bone disease rather than curing it.
Used to help with: Bone pain.
“Bisphosphonates have proven their effectiveness on bone pain and the limitation of fibrous dysplasia.”
aromatase inhibitors
Aromatase inhibitors (such as letrozole) are used to control early puberty by lowering estrogen production, helping suppress pubertal progression.
Used to help with: Precocious puberty.
“The patient initially presented with peripheral precocious puberty at age 1 and was treated with aromatase inhibitors and selective estrogen receptor modulator (SERM) until the age of 12 years for pubertal suppression.”
What changes how it shows up
Carrying the genetic change is not the whole story. The factors below are described in the research mapped here as changing whether, or how strongly, the condition appears. They modulate how the genotype is expressed; they do not, on their own, cause or cure it.
somatic mosaicism
Because the GNAS change is present in only some cells (mosaicism), which cells carry it differs from person to person. This is why the condition looks so different between individuals and why a blood test can miss it.
Described as modulating: McCune-Albright syndrome, somatic, mosaic.
“Mosaicism leads to marked clinical heterogeneity and complicates molecular diagnosis.”
Turn this into questions for your doctor
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How to read the evidence labels
Where this comes from
This guide is built from 4 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.