RecruitingNCT00001727
Connective Tissue
McCune-Albright Syndrome
Also known as polyostotic fibrous dysplasia, McCune-Albright, GNAS mosaic mutation
McCune-Albright syndrome results from a somatic activating mutation in GNAS, encoding the Gsalpha subunit of heterotrimeric G-proteins, arising postzygotically and thus present in mosaic distribution throughout affected tissues. The classic
ORPHA:562 ↗Gene GNASPrevalence 1 in 100,000–1,000,000Onset Congenital (postzygotic mutation); clinical presentation in infancy to childhoodGenetic — somatic mosaic (postzygotic, not heritable)
4
studies recruiting now
as of 7 Sept 2026
25
studies registered in total
as of 7 Sept 2026
3
countries with a recruiting site
as of 7 Sept 2026
6 May 2026
most recent study posted
among recruiting studies
Recruiting trials
RecruitingNCT07569731
Fibrous Dysplasia: An Epidemiological and Correlational Evaluation of Multimodal Data
RecruitingNCT03231644
Fibrous Dysplasia, McCune-Albright Syndrome Patient Registry
RecruitingPhase 4NCT05966064
DEnosumab for the Treatment of FIbrous Dysplasia/McCune-Albright Syndrome in Adults (DeFiD)
Showing the 4 most recently updated recruiting studies, as recorded 7 Sept 2026. Live status on each study page.
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Countries with at least one recruiting site among the studies above, 7 Sept 2026. Tap a country to search trials there.
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About McCune-Albright Syndrome
McCune-Albright syndrome results from a somatic activating mutation in GNAS, encoding the Gsalpha subunit of heterotrimeric G-proteins, arising postzygotically and thus present in mosaic distribution throughout affected tissues. The classic triad consists of polyostotic fibrous dysplasia of bone (fibrous replacement of medullary bone predisposing to pathological fractures and deformity), cafe-au-lait skin macules with irregular borders, and autonomous endocrine hyperfunctioning of the gonads, thyroid, adrenal cortex, or pituitary. Clinical severity is highly variable and determined by the timing of the postzygotic mutation and the tissues in which the mutant clone is represented.
Common clinical features
Polyostotic fibrous dysplasia causing bone pain, deformity, and pathological fracturesCafe-au-lait macules with irregular (coast of Maine) bordersGonadotropin-independent precocious puberty (especially in girls)Hyperthyroidism from autonomous thyroid nodulesCushing syndrome from adrenocortical hyperplasia (in infants)Growth hormone excess and acromegaloid featuresPhosphate wasting and rickets secondary to FGF23 overproduction
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Treatments being studied
3 in clinical development, from Open Targets (CC BY 4.0). Not medical advice.
Phase 3Pegvisomant (Somavert)
Phase 2Anastrozole (Anastrozole)
Phase 2Fulvestrant (Faslodex)
Before you apply
Things trial teams commonly ask about for McCune-Albright Syndrome. Not eligibility rules; those are set by each study.
- Blood or tissue for GNAS mutation testing should ideally include DNA from affected tissue (bone or affected skin), as the mosaic mutation may not be detectable in peripheral blood leukocytes — clarify the testing source with the genetic laboratory.
- Baseline bone scintigraphy (technetium scan) or skeletal survey documenting extent and distribution of fibrous dysplasia lesions is standard prior to enrolment in bone-targeted trials.
- Endocrine assessments (LH, FSH, oestradiol or testosterone, IGF-1, thyroid function, morning cortisol) are required at screening as autonomous hyperfunctioning affects safety and efficacy endpoints.
Related conditions
Information, not medical advice. Trial listings are shown as recorded on ClinicalTrials.gov; whether any study is right for you is a decision for you and your clinicians, and eligibility is decided by each research team. Disease information from Orphanet (CC BY 4.0).