McCune–Albright syndrome

Not to be confused with Albright's hereditary osteodystrophy.

McCune-Albright syndrome
Café-au-lait skin pigmentation. A) A typical lesion on the face, chest, and arm of a 5-year-old girl with McCune-Albright syndrome which demonstrates jagged "coast of Maine" borders, and the tendency for the lesions to both respect the midline and follow the developmental lines of Blaschko. B) Typical lesions that are often found on the nape of the neck and crease of the buttocks are shown (arrows).
Classification and external resources
Specialty	medical genetics
ICD-10	Q78.1
ICD-9-CM	756.54
OMIM	174800
DiseasesDB	7880
MedlinePlus	001217
eMedicine	ped/1386
Patient UK	McCune–Albright syndrome
MeSH	D005359
Orphanet	562

McCune–Albright syndrome is a complex genetic disorder affecting the bone, skin, and endocrine systems.

Signs and symptoms

McCune–Albright syndrome is suspected when one or more of the following features are present:

Hyperfunctioning endocrine disease
Fibrous dysplasia
Café au lait macules

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.

Approximately 20-30% of fibrous dysplasias are polyostotic, which means fibrous dysplasia and sclerotic bone are present in multiple sites; two thirds of patients are polyostotic before the age of ten. 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.

Increased production of hormones by glands regulated by the G protein system is due to a mutation in the gene causing continuous activation of stimulatory G protein. This results in the so-called "autonomous production" of hormones, including thyroid hormone, cortisol, estrogen and growth hormone. Therefore, hyperthyroidism, Cushing syndrome, precocious puberty in women with premature thelarche (breast growth), premature menarche (beginning of menstrual function), increased speed of growth and growth hormone excess can ensue. Increased serum estrogen concentrations correlate with large ovarian cysts. Ovarian cysts appear and disappear with changing estrogen concentrations, causing menstrual bleeding when estrogen decreases.

McCune–Albright syndrome has different levels of severity. For example, one child with McCune–Albright syndrome 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. Diagnosis may be made only after decades. In other cases, children are diagnosed in early infancy, show obvious bone disease, and obvious increased endocrine secretions from several glands.

Genetics

Genetically, there is a postzygotic mutation (spontaneous mutation) of the gene GNAS1, on the long (q) arm of chromosome 20 at position 13.3, which is involved in G-protein signalling.^[1] This mutation, often a mosaicism, prevents downregulation of cAMP signalling.

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).

Notable cases

Mauricio Saravia, a Uruguayan artist with the disease

The disease made headlines in December, 2005 when a Haitian teen affected with the disease, Marlie Casseus, underwent a 17-hour emergency surgical procedure to remove a 7 kg (16 pound) tumour-like growth of bone from her face. A series of operations at Holtz Children's Hospital in Miami, Florida restored the child's face to a more normal proportion.^[2]

References

↑ Collins MT, Sarlis NJ, Merino MJ, et al. (September 2003). "Thyroid carcinoma in the McCune-Albright syndrome: contributory role of activating Gs alpha mutations". J. Clin. Endocrinol. Metab. 88 (9): 4413–7. doi:10.1210/jc.2002-021642. PMID 12970318.
↑ "Marlie Casseus". Archived from the original on 2007-05-29. Retrieved 2007-07-14.

External links

RockYourPaper
Medterms.com
GNAS gene
NORD
GFMER
Fibrous Dysplasia Radiology Image Database

Osteochondrodysplasia (Q77–Q78, 756.4–756.5)

Osteodysplasia//
osteodystrophy

Diaphysis	Camurati–Engelmann disease

Metaphysis	Metaphyseal dysplasia Jansen's metaphyseal chondrodysplasia Schmid metaphyseal chondrodysplasia

Epiphysis	Spondyloepiphyseal dysplasia congenita Multiple epiphyseal dysplasia Otospondylomegaepiphyseal dysplasia

Osteosclerosis	Raine syndrome Osteopoikilosis Osteopetrosis

Other/ungrouped	FLNB Boomerang dysplasia Opsismodysplasia Polyostotic fibrous dysplasia McCune–Albright syndrome

Chondrodysplasia/
chondrodystrophy
(including dwarfism)

Osteochondroma

osteochondromatosis
- Hereditary multiple exostoses

Chondroma/enchondroma

enchondromatosis
- Ollier disease
- Maffucci syndrome

Growth factor receptor

FGFR2:	Antley–Bixler syndrome

FGFR3:	Achondroplasia Hypochondroplasia Thanatophoric dysplasia

COL2A1 collagen disease

SLC26A2 sulfation defect

Chondrodysplasia punctata

Other dwarfism

Deficiencies of intracellular signaling peptides and proteins

GTP-binding protein regulators

GTPase-activating protein	Neurofibromatosis type I Watson syndrome Tuberous sclerosis

Guanine nucleotide exchange factor	Marinesco–Sjögren syndrome Aarskog–Scott syndrome Juvenile primary lateral sclerosis X-Linked mental retardation 1

G protein

Heterotrimeic	cAMP/GNAS1: Pseudopseudohypoparathyroidism Progressive osseous heteroplasia Pseudohypoparathyroidism Albright's hereditary osteodystrophy McCune–Albright syndrome CGL 2

Monomeric	RAS: HRAS Costello syndrome KRAS Noonan syndrome 3 KRAS Cardiofaciocutaneous syndrome RAB: RAB7 Charcot–Marie–Tooth disease RAB23 Carpenter syndrome RAB27 Griscelli syndrome type 2 RHO: RAC2 Neutrophil immunodeficiency syndrome ARF: SAR1B Chylomicron retention disease ARL13B Joubert syndrome 8 ARL6 Bardet–Biedl syndrome 3

MAP kinase

Cardiofaciocutaneous syndrome

Other kinase/phosphatase

Tyrosine kinase	BTK X-linked agammaglobulinemia ZAP70 ZAP70 deficiency

Serine/threonine kinase	RPS6KA3 Coffin-Lowry syndrome CHEK2 Li-Fraumeni syndrome 2 IKBKG Incontinentia pigmenti STK11 Peutz–Jeghers syndrome DMPK Myotonic dystrophy 1 ATR Seckel syndrome 1 GRK1 Oguchi disease 2 WNK4/WNK1 Pseudohypoaldosteronism 2

Tyrosine phosphatase	PTEN Bannayan–Riley–Ruvalcaba syndrome Lhermitte–Duclos disease Cowden syndrome Proteus-like syndrome MTM1 X-linked myotubular myopathy PTPN11 Noonan syndrome 1 LEOPARD syndrome Metachondromatosis

Signal transducing adaptor proteins

Other

NF2
- Neurofibromatosis type II
NOTCH3
- CADASIL
PRKAR1A
- Carney complex
PRKAG2
- Wolff–Parkinson–White syndrome
PRKCSH
- PRKCSH Polycystic liver disease
XIAP
- XIAP2

See also intracellular signaling peptides and proteins

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