McCune-Albright syndrome
| McCune-Albright syndrome | |
| ICD-10 | Q78.1 |
|---|---|
| ICD-9 | 756.54 |
| OMIM | 174800 |
| DiseasesDB | 7880 |
| MedlinePlus | 001217 |
| eMedicine | ped/1386 |
| MeSH | D005359 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
McCune-Albright syndrome is a rare genetic disorder caused by an activating mutation of the GNAS gene resulting in various phenotypic presentations. MAS typically presents with the triad of polyostotic fibrous dysplasia, precocious puberty and café au lait spots in both genders. Other manifestations include hyperthyroidism, acromegaly and Cushing’s syndrome.[1]
Historical Perspective
Classification
Pathophysiology
Causes
Differentiation McCune-Albright syndrome from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Criteria
Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
X-ray
Echocardiography or Ultrasound
CT scan
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
References
- ↑ "StatPearls". 2020. PMID https://www.ncbi.nlm.nih.gov/pubmed/30725777 Check
|pmid=value (help).
Presentation
Within the syndrome there are bone fractures and deformity of the legs, arms and skull, different pigment patches on the skin, and early puberty with increased rate of growth.
Polyostotic fibrous dysplasia has different levels of severity. For example one child may be entirely healthy with no outward evidence of bone or endocrine problems, enter puberty at close to the normal age and have no unusual skin pigmentation. The complete opposite of that would be children who are diagnosed in early infancy with the obvious bone disease and obvious increased endocrine secretions from several glands.
Approximately 20-30% of fibrous dysplasias are polyostotic and two thirds of patients are polyostotic before the age of ten.
Polyostotic fibrous dysplasia is usually caused by mosaicism for a mutation in a gene called GNAS1 (Guanine Nucleotide binding protein, Alpha Stimulating activity polypeptide 1).
The syndrome shows a broad spectrum of severity. The disease frequently involves the skull and facial bones, pelvis, spine and shoulder girdle. The sites of involvement are the femur (91%), tibia (81%), pelvis (78%), ribs, skull and facial bones (50%), upper extremities, lumbar spine, clavicle, and cervical spine, in decreasing order of frequency. The craniofacial pattern of the disease occurs in 50% of patients with the polyostotic form of fibrous dysplasia.
Genetics
Genetically, there is a post-zygotic mutation of the gene GNAS1 which is involved in G-protein signalling. This mutation, often a mosaicism, prevents downregulation of cAMP signalling.