Identification of a mutation in the gene encoding the alpha subunit of the stimulatory G protein of adenylyl cyclase in McCune-Albright syndrome

Clinical guidelines for the management of craniofacial fibrous dysplasia

Fibrous dysplasia (FD) is a non-malignant condition caused by post-zygotic, activating mutations of the GNAS gene that results in inhibition of the differentiation and proliferation of bone-forming stromal cells and leads to the replacement of normal bone and marrow by fibrous tissue and woven bone. The phenotype is variable and may be isolated to a single skeletal site or multiple sites and sometimes is associated with extraskeletal manifestations in the skin and/or endocrine organs (McCune-Albright syndrome). The clinical behavior and progression of FD may also vary, thereby making the management of this condition difficult with few established clinical guidelines. This paper provides a clinically-focused comprehensive description of craniofacial FD, its natural progression, the components of the diagnostic evaluation and the multi-disciplinary management, and considerations for future research.

McCune-Albright syndrome and the extraskeletal manifestations of fibrous dysplasia

Fibrous dysplasia (FD) is sometimes accompanied by extraskeletal manifestations that can include any combination of café-au-lait macules, hyperfunctioning endocrinopathies, such as gonadotropin-independent precocious puberty, hyperthyroidism, growth hormone excess, FGF23-mediated renal phosphate wasting, and/or Cushing syndrome, as well as other less common features. The combination of any of these findings, with or without FD, is known as McCune-Albright syndrome (MAS). The broad spectrum of involved tissues and the unpredictable combination of findings owe to the fact that molecular defect is due to dominant activating mutations in the widely expressed signaling protein, Gsα, and the fact these mutations arises sporadically, often times early in development, prior to gastrulation, and can distribute across many or few tissues.The complexity can be mastered by a systematic screening of potentially involved tissues and cognizance that the pattern of involved tissues is established, to some degree, in utero. Thorough testing allows the clinician to establish, often times at presentation, the full extent of the disease, and importantly as well what tissues are unaffected. Treatment and follow-up can then be focused on affected systems and a meaningful prognosis can be offered to the patient and family. The authors outline screening and treatment strategies that allow for effective management of the extraskeletal manifestations of FD.

FGF23 and syndromes of abnormal renal phosphate handling

Fibroblast growth factor 23 (FGF23) is part of a previously unrecognized hormonal bone-parathyroid-kidney axis, which is modulated by 1,25(OH)(2)-vitamin D (1,25(OH)(2)D), dietary and circulating phosphate and possibly PTH. FGF23 was discovered as the humoral factor in tumors that causes hypophosphatemia and osteomalacia and through the identification of a mutant form of FGF23 that leads to autosomal dominant hypophosphatemic rickets (ADHR), a rare genetic disorder. FGF23 appears to be mainly secreted by osteocytes where its expression is up-regulated by 1,25(OH)(2)D and probably by increased serum phosphate levels. Its synthesis and secretion is reduced through yet unknown mechanisms that involve the phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX), dentin matrix protein 1 (DMP1) and ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Consequently, loss-of-function mutations in these genes underlie hypophosphatemic disorders that are either X-linked or autosomal recessive. Impaired O-glycosylation of FGF23 due to the lack of UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyl-transferase 3 (GALNT3) or due to certain homozygous FGF23 mutations results in reduced secretion of intact FGF23 and leads to familial hyperphosphatemic tumoral calcinosis. FGF23 acts through FGF-receptors and the coreceptor Klotho to reduce 1,25(OH)(2)D synthesis in the kidney and probably the synthesis of parathyroid hormone (PTH) by the parathyroid glands. It furthermore synergizes with PTH to increase renal phosphate excretion by reducing expression of the sodium-phosphate cotransporters NaPi-IIa and NaPi-IIc in the proximal tubules. Loss-of-function mutations in these two transporters lead to autosomal recessive Fanconi syndrome or to hereditary hypophosphatemic rickets with hypercalciuria, respectively.

Pigmentary nevi on face have unique patterns and implications: The concept of Blaschko's lines for pigmentary nevi

Background:

Nevi are proposed to reflect the mosaicism and thus generally follow the different archetypal patterns of mosaicism. Blaschko's lines are the most common pattern of mosaicism. There have been many attempts to elucidate the Blaschko's lines on face from the distributional patterns of different nevi, but studies that evaluated exclusively pigmentary nevi are sparse. Aims: This study attempted to evaluate the patterns followed by different pigmentary nevi on face and utilized this to elucidate the pattern of embryological pigmentation on face.

Materials and Methods:

Spatial parameters like shape, orientation, and distribution patterns of different flat pigmentary nevi on face were analyzed and graphically drawn on human facial diagram. This was compared with existing facial Blaschko's lines. All cases of palpable pigmented nevi like congenital and giant melanocytic nevi and nevus spilus were excluded.

Results:

A total of 68 cases of pigmentary nevi on face (male-39, female-29) were examined. The shape and distribution lines were found to have a close similarity with Blaschko's lines on face with distinct differences.

Conclusions:

The concept of facial embryonic pigmentary ‘segment’, ‘unit’ and existence of separate Blaschko's lines for facial pigmentary nevi is conceived. Some insight into the pathogenesis of Blaschko's lines is also proposed in this study.

Polyostotic fibrous dysplasia of the thoracic spine: case report and review of the literature

STUDY DESIGN

A case report of polyostotic fibrous dysplasia including thoracic spine, sacral vertebrae, and temporal bone, with the symptom of back pain.

OBJECTIVE

To treat the lesions with percutaneous kyphoplasty.

SUMMARY OF BACKGROUND DATA

Polyostotic fibrous dysplasia involving either spine or temporal bone is rarely seen. Few reports of this disorder appear in the literature. This is the first case including thoracic spine, sacrum, and temporal bone together presented to date.

METHODS

The patient was a 56-year-old woman with polyostotic fibrous dysplasia involving the thoracic spine of the eighth, ninth, and 10th vertebral body; adjacent rib; the right temporal bone and the sacrum. Percutaneous kyphoplasty in ninth and 10th vertebral body was carried out to achieve substantial pain relief and rapid stabilization of the spine with minimal invasion.

RESULTS

The patient experienced complete pain relief and had no clinical complications associated with the cement leakage. The patient tolerated the procedure well. There were no clinical complications and substantial pain relief was noted within hours of the procedure. She has no pain or disability at 1-year follow-up.

CONCLUSION

Percutaneous kyphoplasty was a good therapeutic option for the reported patient.

Surgery versus watchful waiting in patients with craniofacial fibrous dysplasia--a meta-analysis

Background

Fibrous dysplasia (FD) is a benign bone tumor which most commonly involves the craniofacial skeleton. The most devastating consequence of craniofacial FD (CFD) is loss of vision due to optic nerve compression (ONC). Radiological evidence of ONC is common, however the management of this condition is not well established. Our objective was to compare the long-term outcome of patients with optic nerve compression (ONC) due to craniofacial fibrous dysplasia (CFD) who either underwent surgery or were managed expectantly.

Methodology/Principal Findings

We performed a meta-analysis of 27 studies along with analysis of the records of a cohort of patients enrolled in National Institutes of Health (NIH) protocol 98-D-0145, entitled Screening and Natural History of Fibrous Dysplasia, with a diagnosis of CFD. The study group consisted of 241 patients; 122 were enrolled in the NIH study and 119 were extracted from cases published in the literature. The median follow-up period was 54 months (range, 6–228 months). A total of 368 optic nerves were investigated. All clinically impaired optic nerves (n = 86, 23.3%) underwent therapeutic decompression. Of the 282 clinically intact nerves, 41 (15%) were surgically decompressed and 241 (85%) were followed expectantly. Improvement in visual function was reported in fifty-eight (67.4%) of the clinically impaired nerves after surgery. In the intact nerves group, long-term stable vision was achieved in 31/45 (75.6%) of the operated nerves, compared to 229/241 (95.1%) of the non-operated ones (p = 0.0003). Surgery in asymptomatic patients was associated with visual deterioration (RR 4.89; 95% CI 2.26–10.59).

Conclusions

Most patients with CFD will remain asymptomatic during long-term follow-up. Expectant management is recommended in asymptomatic patients even in the presence of radiological evidence of ONC.

Extra-long Gαs variant XLαs protein escapes activation-induced subcellular redistribution and is able to provide sustained signaling

Murine models indicate that Gαs and its extra-long variant XLαs, both of which are derived from GNAS, markedly differ regarding their cellular actions, but these differences are unknown. Here we investigated activation-induced trafficking of Gαs and XLαs, using immunofluorescence microscopy, cell fractionation, and total internal reflection fluorescence microscopy. In transfected cells, XLαs remained localized to the plasma membrane, whereas Gαs redistributed to the cytosol after activation by GTPase-inhibiting mutations, cholera toxin treatment, or G protein-coupled receptor agonists (isoproterenol or parathyroid hormone (PTH)(1-34)). Cholera toxin treatment or agonist (isoproterenol or pituitary adenylate cyclase activating peptide-27) stimulation of PC12 cells expressing Gαs and XLαs endogenously led to an increased abundance of Gαs, but not XLαs, in the soluble fraction. Mutational analyses revealed two conserved cysteines and the highly charged domain as being critically involved in the plasma membrane anchoring of XLαs. The cAMP response induced by M-PTH(1-14), a parathyroid hormone analog, terminated quickly in HEK293 cells stably expressing the type 1 PTH/PTH-related peptide receptor, whereas the response remained maximal for at least 6 min in cells that co-expressed the PTH receptor and XLαs. Although isoproterenol-induced cAMP response was not prolonged by XLαs expression, a GTPase-deficient XLαs mutant found in certain tumors and patients with fibrous dysplasia of bone and McCune-Albright syndrome generated more basal cAMP accumulation in HEK293 cells and caused more severe impairment of osteoblastic differentiation of MC3T3-E1 cells than the cognate Gαs mutant (gsp oncogene). Thus, activated XLαs and Gαs traffic differently, and this may form the basis for the differences in their cellular actions.

The GNAS Locus: Quintessential Complex Gene Encoding Gsalpha, XLalphas, and other Imprinted Transcripts

The currently estimated number of genes in the human genome is much smaller than previously predicted. As an explanation for this disparity, most individual genes have multiple transcriptional units that represent a variety of biologically important gene products. GNAS exemplifies a gene of such complexity. One of its products is the alpha-subunit of the stimulatory heterotrimeric G protein (Gsalpha), a ubiquitous signaling protein essential for numerous different cellular responses. Loss-of-function and gain-of-function mutations within Gsalpha-coding GNAS exons are found in various human disorders, including Albright's hereditary osteodystrophy, pseudohypoparathyroidism, fibrous dysplasia of bone, and some tumors of different origin. While Gsalpha expression in most tissues is biallelic, paternal Gsalpha expression is silenced in a small number of tissues, playing an important role in the development of phenotypes associated with GNAS mutations. Additional products derived exclusively from the paternal GNAS allele include XLalphas, a protein partially identical to Gsalpha, and two non-coding RNA molecules, the A/B transcript and the antisense transcript. The maternal GNAS allele leads to NESP55, a chromogranin-like neuroendocrine secretory protein. In vivo animal models have demonstrated the importance of each of the exclusively imprinted GNAS products in normal mammalian physiology. However, although one or more of these products are also disrupted by most naturally occurring GNAS mutations, their roles in disease pathogenesis remain unknown. To further our understanding of the significance of this gene in physiology and pathophysiology, it will be important to elucidate the cellular roles and the mechanisms regulating the expression of each GNAS product.

Quantitative analysis of activating alpha subunit of the G protein (Gsα) mutation by pyrosequencing in fibrous dysplasia and other bone lesions

Benign fibro-osseous lesions (BFOLs) frequently display overlapping histological features. The differentiation of fibrous dysplasia (FD) from other BFOLs can be difficult, even for experienced orthopedic pathologists. Accurately distinguishing FD from other BFOLs may have significant clinical and treatment implications. A somatic mutation in gene GNAS encoding the α subunit of the G protein (Gsα) involving the codon corresponding to Arg 201 has been identified in FD and is specifically absent in other BFOLs. We have developed a quantitative assay by pyrosequencing that has a detection sensitivity of 95%. The test allows the identification of the two most common types of mutation (Arg→His and Arg→Cys) in a single reaction, with the ability to analyze other rare mutations. Of the 24 FD cases in this series, 23 (96%) were positive for GNAS/Gsα mutation. Nineteen of 23 positive cases exhibited a G→A mutation (Arg→His), whereas four had a C→T mutation (Arg→Cys). One of three BFOL, not otherwise specified cases was positive for G→A mutation. None of the osteofibrous dysplasia, ossifying fibromas, or other bone lesions were positive for this mutation. Our experience is that pyrosequencing is an easy and accurate quantification method for Gsα mutation detection in fibrous dysplasia. Mutation analysis of the Gsα by pyrosequencing has significant potential for improving discrimination between FD and other BFOLs in problematic cases.

Craniofacial fibrous dysplasia: clinical characteristics and long-term outcomes

AIM

To present the clinical features and management outcomes in a large longitudinal series of patients with craniofacial fibrous dysplasia (CFD).

METHODS

Retrospective interventional consecutive case series. Main outcome measures included signs and symptoms, radiographic findings, long-term outcomes, and postoperative complications.

RESULTS

A total of 42 patients with CFD were identified. The mean age at presentation was 16.7 years; mean follow-up was 12.6 years. Out of these 42 patients, 37 (88.1%) had unilateral involvement and 5 (11.9%) had bilateral involvement, of which 3 (7.1%) had McCune-Albright syndrome. The commonest presenting symptom was facial asymmetry (36 cases, 86%). The frontal bone was the most commonly involved (27 cases, 64.3%), zfollowed by the sphenoid (24 cases, 57.1%). The most common pattern of bone involvement was monostotic (32 cases, 76.2%). Radiological optic canal involvement occurred in 18 eyes of 15 (37.5%) patients, with optic atrophy in 9 eyes (18.8%) of 7 patients (16.7%). Surgical intervention was performed in 30 (71.4%) cases for both functional and reconstructive reasons. Optic canal decompression was performed in three cases, in all of which stabilization of vision was achieved; no patient lost vision as a result of surgery.

CONCLUSIONS

In this large longitudinal series of CFD, visual loss was not uncommon and occurred insidiously. The presenting clinical and radiological features, surgical interventions, and outcomes are discussed.

Potent constitutive cyclic AMP-generating activity of XLαs implicates this imprinted GNAS product in the pathogenesis of McCune-Albright syndrome and fibrous dysplasia of bone

Patients with McCune-Albright syndrome (MAS), characterized primarily by hyperpigmented skin lesions, precocious puberty, and fibrous dyslasia of bone, carry postzygotic heterozygous mutations of GNAS causing constitutive cAMP signaling. GNAS encodes the α-subunit of the stimulatory G protein (Gsα), as well as a large variant (XLαs) derived from the paternal allele. The mutations causing MAS affect both GNAS products, but whether XLαs, like Gsα, can be involved in the pathogenesis remains unknown. Here, we investigated biopsy samples from four previously reported and eight new patients with MAS. Activating mutations of GNAS (Arg201 with respect to the amino acid sequence of Gsα) were present in all the previously reported and five of the new cases. The mutation was detected within the paternally expressed XLαs transcript in five and the maternally expressed NESP55 transcript in four cases. Tissues carrying paternal mutations appeared to have higher XLαs mRNA levels than maternal mutations. The human XLαs mutant analogous to Gsα-R201H (XLαs-R543H) showed markedly higher basal cAMP accumulation than wild-type XLαs in transfected cells. Wild-type XLαs demonstrated higher basal and isoproterenol-induced cAMP signaling than Gsα and co-purified with Gβ1γ2 in transduced cells. XLαs mRNA was measurable in mouse calvarial cells, with its level being significantly higher in undifferentiated cells than those expressing preosteoblastic markers osterix and alkaline phosphatase. XLαs mRNA was also expressed in murine bone marrow stromal cells and preosteoblastic MC3T3-E1 cells. Our findings are consistent with the possibility that constitutive XLαs activity adds to the molecular pathogenesis of MAS and fibrous dysplasia of bone.

Diseases associated with genomic imprinting

Genomic imprinting is the phenomenon where the expression of a locus differs between the maternally and paternally inherited alleles. Typically, this manifests as transcriptional silencing of one of the alleles, although many genes are imprinted in a tissue- or isoform-specific manner. Diseases associated with imprinted genes include various cancers, disorders of growth and metabolism, and disorders in neurodevelopment, cognition, and behavior, including certain major psychiatric disorders. In many cases, the disease phenotypes associated with dysfunction at particular imprinted loci can be understood in terms of the evolutionary processes responsible for the origin of imprinting. Imprinted gene expression represents the outcome of an intragenomic evolutionary conflict, where natural selection favors different expression strategies for maternally and paternally inherited alleles. This conflict is reasonably well understood in the context of the early growth effects of imprinted genes, where paternally inherited alleles are selected to place a greater demand on maternal resources than are maternally inherited alleles. Less well understood are the origins of imprinted gene expression in the brain, and their effects on cognition and behavior. This chapter reviews the genetic diseases that are associated with imprinted genes, framed in terms of the evolutionary pressures acting on gene expression at those loci. We begin by reviewing the phenomenon and evolutionary origins of genomic imprinting. We then discuss diseases that are associated with genetic or epigenetic defects at particular imprinted loci, many of which are associated with abnormalities in growth and/or feeding behaviors that can be understood in terms of the asymmetric pressures of natural selection on maternally and paternally inherited alleles. We next described the evidence for imprinted gene effects on adult cognition and behavior, and the possible role of imprinted genes in the etiology of certain major psychiatric disorders. Finally, we conclude with a discussion of how imprinting, and the evolutionary-genetic conflicts that underlie it, may enhance both the frequency and morbidity of certain types of diseases.

Ovarian function in adolescents with McCune-Albright syndrome

OBJECTIVE

To evaluate ovarian function, especially ovulation rate, in adolescents with McCune-Albright syndrome (MAS) and a history of peripheral precocious puberty.

DESIGN

Prospective cross-sectional study.

SETTING

Academic center.

PATIENT(S)

A total of eight adolescents with MAS were compared with 15 healthy adolescents matched by age, Tanner stage and body mass index.

INTERVENTION(S)

We determined basal gonadotropins, sex steroids, sex hormone binding globulin, anti-Müllerian hormone, glucose and insulin. A leuprolide acetate test was performed to measure luteinizing hormone (LH) and follicle stimulating hormone (FSH) (at 0 and 3 h), and 17B-estradiol, testosterone and 17-OH-progesterone (at 0 and 24 h). Salivary progesterone levels were used to assess ovulation during the 13th, 18th, 23rd and 28th days of each menstrual cycle for three to five consecutive cycles, and one pelvic ultrasound was performed during the follicular phase.

MAIN OUTCOME MEASURE(S)

Ovulation rate in adolescents with MAS.

RESULT(S)

The proportion of ovulatory cycles was 52.6% in controls compared with 35.7% in patients with MAS.

CONCLUSION(S)

The adolescent girls with MAS appear to have a lower ovulatory rate compared with controls.

Skeletal progenitors and the GNAS gene: fibrous dysplasia of bone read through stem cells

Activating mutations of the GNAS gene, which causes fibrous dysplasia of bone (FD), lead to remarkable changes in the properties of skeletal progenitors, and it is these changes that mediate the pathological effect of this gene on bone. Mutated skeletal stem cells lose the ability to differentiate into adipocytes, and to maintain in situ, and transfer heterotopically, the hematopoietic microenvironment, leading to abnormal bone marrow histology in FD. They overexpress molecular effectors of osteoclastogenesis, thus promoting inappropriate bone resorption leading to fragility of FD bone. They express the phosphate-regulating hormone FGF-23 at normal levels, whose excess in the serum of FD patients correlates with the mass of osteogenic cells within FD lesions, leading to osteomalacia and deformity of the FD bone, and revealing that bone is an endocrine organ regulating renal handling of phosphate. Mechanisms of allelic selection and stem cell selection occur in mutated skeletal stem cells and contribute to the inherent diversity and evolution over time in FD. The definition of the etiological role of GNAS mutations marks the watershed between many decades of descriptive observation and the definition of cellular and molecular mechanisms that would explain and hopefully allow for a cure for the disease. Placing stem cells at center stage has permitted substantial advances in one decade, and promises more for the one to come.

The diagnostic and clinical significance of café-au-lait macules

Café-au-lait, also referred to as café-au-lait spots or café-au-lait macules, present as well-circumscribed, evenly pigmented macules and patches that range in size from 1 to 2 mm to greater than 20 cm in greatest diameter. Café-au-lait are common in children. Although most café-au-lait present as 1 or 2 spots in an otherwise healthy child, the presence of multiple café-au-lait, large segmental café-au-lait, associated facial dysmorphism, other cutaneous anomalies, or unusual findings on physical examination should suggest the possibility of an associated syndrome. While neurofibromatosis type 1 is the most common syndrome seen in children with multiple café-au-lait, other syndromes associated with one or more café-au-lait include McCune-Albright syndrome, Legius syndrome, Noonan syndrome and other neuro-cardio-facialcutaneous syndromes, ring chromosome syndromes, and constitutional mismatch repair deficiency syndrome.

Polyostotic fibrous dysplasia with gigantism and huge pelvic tumor: a rare case of McCune-Albright syndrome

We report a rare case of polyostotic fibrous dysplasia on endocrine hyperfunction with elevated human growth hormone and normal serum level of prolactin. There were some differential points of gender, gigantism, endocrine function, and GNAS gene from McCune-Albright syndrome. Malignant transformation was suspected in the pelvic tumor from imaging because rapid growth of the tumor by imaging was observed; however, no malignant change occurred in this case.

McCune-Albright syndrome (MAS): early and extensive bone fibrous dysplasia involvement and "mistaken identity" oophorectomy

BACKGROUND

McCune-Albright syndrome (MAS) is a triad of gonadotropin-independent precocious puberty (GIPP), café-au-lait spots (CALS) and fibrous dysplasia (FD) of bone. The extent of the abnormalities is variable.

PATIENT AND RESULTS

We report a 3 year old girl with CALS since infancy, FD diagnosed at age of 2.5 years, and at the age of 3 years vaginal bleeding. The ultrasound revealed a cystic mass of the ovary, surgical pathology found ovarian cyst. LHRH stimulation demonstrated GIPP (LH 9.8 mIU/ml and FSH 8.9 mIU/ml; normal LH 1.8-10, FSH 9-26 mIU/ml). Radiographs and bone scans demonstrated FD in multiple bones. Peripheral leucocytes and the ovary were negative for GNAS gene mutations. Treatment with Letrasole interrupted the pubertal development.

CONCLUSIONS

We conclude that the clinical signs of MAS are telling and that timely MAS diagnosis prevents unnecessary oophorectomy. A close follow up is recommended regarding development of endocrine disorders and spreading of FD.

Twenty classic hand radiographs that lead to diagnosis

Most of the common skeletal dysplasias have some manifestation in the hand. Many have characteristic findings in the hand that lead to the diagnosis. Hand bones are also affected in many systemic hematologic and metabolic conditions. The diagnosis can be clinched on a single hand radiograph if characteristic findings are present. This pictorial essay illustrates characteristic findings of 20 common conditions including bone dysplasias and metabolic and hematologic abnormalities on a single hand radiograph. It also includes some common hand abnormalities without systemic skeletal abnormalities.

Patterns in naevoid skin disease: development, disease and modelling

The aetiology of pattern-formation in human naevoid skin disease remains unknown. However, it is likely that the majority of previously proposed mechanisms - those that simply rely on passive clonal trafficking in embryogenesis - are incomplete. A more comprehensive explanation for pattern-formation in naevi invokes the principle of self-organization. We define two types of patterning: anatomical and functional. Anatomical patterning is where the abnormal clone is limited to regions of pathologic skin, while functional patterning is where the abnormal clone and pathologic skin are spatially uncorrelated. From a theoretical perspective self-organized naevoid patterns may be either secondary to local interactions between normal and aberrant genotypes or due to the interaction between aberrant genotypes and the presence of normal embryonic patterning cues. The latter possibility suggests the critical observation and analysis of patterns in naevoid skin disease may lead to unique insights into key aspects of early human embryogenesis.

Regulation of phosphate transport by fibroblast growth factor 23 (FGF23): implications for disorders of phosphate metabolism

There are a number of hypophosphatemic disorders due to renal phosphate wasting that cannot be explained by elevated levels of parathyroid hormone. The circulating factors responsible for the phosphaturia have been designated as phosphatonins. Studies of patients with tumor-induced osteomalacia and other genetic diseases of phosphate metabolism have resulted in the identification of a number of hormones that regulate phosphate homeostasis, including matrix extracellular phosphoglycoprotein (MEPE), secreted frizzled-related protein 4 (sFRP-4), dentin matrix protein 1 (DMP1), fibroblast growth factor 7 (FGF7), fibroblast growth factor 23 (FGF23), and Klotho. Our understanding of the actions of these hypophosphatemic peptides has been enhanced by studies in mice either overexpressing or not expressing these hormones. This review focuses on FGF23 since its regulation is disordered in diseases that affect children, such as X-linked hypophosphatemia, autosomal dominant and recessive hypophosphatemic rickets as well as chronic kidney disease. Recent studies have shown that FGF23 is unique among the FGFs in its requirement for Klotho for receptor activation. Here, we also discuss new potentially clinically important data pointing to the receptor(s) that mediate the binding and action of FGF23 and Klotho.

Cushing syndrome in the McCune-Albright syndrome

CONTEXT

Cushing syndrome (CS) is a rare but potentially fatal feature of McCune-Albright syndrome (MAS). Optimal management, prognostic features, and long-term follow-up of this disorder have not been described.

SETTING

The study was conducted at an academic tertiary care center.

PATIENTS

A total of 112 patients participating in a natural history study at the National Institutes of Health (NIH) were evaluated, and 21 published cases were reviewed.

INTERVENTIONS

Subjects received observation, medical management, or bilateral adrenalectomy.

MAIN OUTCOME MEASURES

We measured prevalence, prognostic factors, and natural history.

RESULTS

The prevalence of CS among NIH patients was 7.1%. The median age at diagnosis was 3 months. Clinical features included "Cushingoid facies" (66.7%), failure to thrive (60.0%), low birth weight (50.0%), liver disease (36.7%), and heart disease (26.7%). Six patients (20.0%) died, four after adrenalectomy. Death was more likely in patients with comorbid heart disease (odds ratio, 13.3; P < 0.05). Of 23 survivors, 13 underwent adrenalectomy, and 10 exhibited spontaneous resolution. Two patients with spontaneous resolution who were tested later in life (3 and 15 yr after resolution) continued to have low-level, autonomous adrenal function with biochemical adrenal insufficiency. Compared to MAS patients without CS, patients with CS were more likely to have a cognitive/developmental disorder (44.4 vs. 4.8%; P < 0.001; odds ratio, 8.8).

CONCLUSIONS

Comorbid heart and liver disease were poor prognostic markers and may indicate the need for prompt adrenalectomy. The high incidence of cognitive disorders indicates a need for close developmental follow-up and parental counseling. Patients with spontaneous resolution of CS may develop adrenal insufficiency, and they require long-term monitoring.

Benefits of molecular pathology in the diagnosis of musculoskeletal disease : Part II of a two-part review: bone tumors and metabolic disorders

The second part of this review, on the benefits of molecular pathology in the diagnosis disease, focuses on the genetics of bone tumors and metabolic disease. Unlike soft tissue tumors, the number of currently exploitable molecular abnormalities for diagnosing bone neoplasms is small, although the same gene rearrangements are found in primitive neuroectodermal tumor/Ewing sarcoma in both skeletal and extraskeletal sites. Compared with soft tissue tumors, genetic abnormalities, which are valuable to diagnosticians in skeletal disease, are often germline and post-zygotic aberrations rather than somatic translocations. In addition, the review highlights the range of disease entities classified as "osteoclast-rich lesions," some of which harbor germline mutations. It also addresses the importance of phosphate metabolism in skeletal disorders including phosphaturic mesenchymal tumor, vitamin D-resistant rickets, and tumoral calcinosis.

New approaches for modelling sporadic genetic disease in the mouse

Sporadic diseases, which occur as single, scattered cases, are among the commonest causes of human morbidity and death. They result in a variety of diseases, including many cancers, premature aging, neurodegeneration and skeletal defects. They are often pathogenetically complex, involving a mosaic distribution of affected cells, and are difficult to model in the mouse. Faithful models of sporadic diseases require innovative forms of genetic manipulation to accurately recreate their initiation and pathogenesis. Such modelling is crucial to understanding these diseases and, by extension, to the development of therapeutic approaches to treat them. This article focuses on sporadic diseases with a genetic aetiology, the challenges they pose to biomedical researchers, and the different current and developing approaches used to model such disorders in the mouse.

Osteosarcoma in a pregnant patient with McCune-Albright syndrome

Malignant transformation of fibrous dysplasia is very rare and has not been previously described in patients with McCune-Albright syndrome in the absence of radiation treatment during gestation. Here, we report a 38-year-old pregnant woman with McCune-Albright syndrome and acromegaly accompanied by osteosarcoma. The patient was in the 6th week of pregnancy, when she visited our hospital. She had multiple fibrous dysplasia, skin pigmentation, and acromegaly. The markedly high bone turnover rate during pregnancy tended to decrease after a normal delivery. Fibrous dysplasia of the lower jaw rapidly increased in the 37th week of pregnancy, and the tumor was surgically resected after delivery. Pathological examination of the resected tumor revealed fibrous dysplasia admixed with osteosarcoma containing chondroblastic and osteoblastic tissue. We firstly reported a case of osteosarcoma in a patient with McCune-Albright syndrome, which rapidly progressed during pregnancy.

Extralarge XL(alpha)s (XXL(alpha)s), a variant of stimulatory G protein alpha-subunit (Gs(alpha)), is a distinct, membrane-anchored GNAS product that can mimic Gs(alpha)

GNAS gives rise to multiple imprinted gene products, including the alpha-subunit of the stimulatory G protein (Gs(alpha)) and its variant XL(alpha)s. Based on genomic sequence, the translation of XL(alpha)s begins from the middle of a long open reading frame, suggesting the existence of an N-terminally extended variant termed extralarge XLalphas (XXL(alpha)s). Although XXL(alpha), like Gs(alpha) and XL(alpha)s, would be affected by most disease-causing GNAS mutations, its authenticity and biological significance remained unknown. Here we identified a mouse cDNA clone that comprises the entire open reading frame encoding XXL(alpha)s. Whereas XXL(alpha)s mRNA was readily detected in mouse heart by RT-PCR, it appeared virtually absent in insulinoma-derived INS-1 cells. By Northern blots and RT-PCR, XXL(alpha)s mRNA was detected primarily in the mouse brain, cerebellum, and spleen. Immunohistochemistry using a specific anti-XXL(alpha)s antibody demonstrated XXL(alpha)s protein in multiple brain areas, including dorsal hippocampus and cortex. In transfected cells, full-length human XXL(alpha)s was localized to the plasma membrane and mediated isoproterenol- and cholera toxin-stimulated cAMP accumulation. XXL(alpha)s-R844H, which bears a mutation analogous to that in the constitutively active Gs(alpha) mutant Gs(alpha)-R201H (gsp oncogene), displayed elevated basal signaling. However, unlike Gs(alpha)-R201H, which mostly remains in the cytoplasm, both XXL(alpha)s-R844H and a constitutively active XL(alpha)s mutant localized to the plasma membrane. Hence, XXL(alpha)s is a distinct GNAS product and can mimic Gs(alpha), but the constitutively active XXL(alpha)s and Gs(alpha) mutants differ from each other regarding subcellular targeting. Our findings suggest that XXL(alpha)s deficiency or hyperactivity may contribute to the pathogenesis of diseases caused by GNAS mutations.

FGF23 decreases renal NaPi-2a and NaPi-2c expression and induces hypophosphatemia in vivo predominantly via FGF receptor 1

Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone that contributes to several hypophosphatemic disorders by reducing the expression of the type II sodium-phosphate cotransporters (NaPi-2a and NaPi-2c) in the kidney proximal tubule and by reducing serum 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] levels. The FGF receptor(s) mediating the hypophosphatemic action of FGF23 in vivo have remained elusive. In this study, we show that proximal tubules express FGFR1, -3, and -4 but not FGFR2 mRNA. To determine which of these three FGFRs mediates FGF23's hypophosphatemic actions, we characterized phosphate homeostasis in FGFR3(-/-) and FGFR4(-/-) null mice, and in conditional FGFR1(-/-) mice, with targeted deletion of FGFR1 expression in the metanephric mesenchyme. Basal serum phosphorus levels and renal cortical brush-border membrane (BBM) NaPi-2a and NaPi-2c expression were comparable between FGFR1(-/-), FGFR3(-/-), and FGFR4(-/-) mice and their wild-type counterparts. Administration of FGF23 to FGFR3(-/-) mice induced hypophosphatemia in these mice (8.0 +/- 0.4 vs. 5.4 +/- 0.3 mg/dl; p < or = 0.001) and a decrease in renal BBM NaPi-2a and NaPi-2c protein expression. Similarly, in FGFR4(-/-) mice, administration of FGF23 caused a small but significant decrease in serum phosphorus levels (8.7 +/- 0.3 vs. 7.6 +/- 0.4 mg/dl; p < or = 0.001) and in renal BBM NaPi-2a and NaPi-2c protein abundance. In contrast, injection of FGF23 into FGFR1(-/-) mice had no effects on serum phosphorus levels (5.6 +/- 0.3 vs. 5.2 +/- 0.5 mg/dl) or BBM NaPi-2a and NaPi-2c expression. These data show that FGFR1 is the predominant receptor for the hypophosphatemic action of FGF23 in vivo, with FGFR4 likely playing a minor role.

Severe arterial hypertension: a possible complication of McCune-Albright syndrome

McCune-Albright syndrome is characterized by café-au-lait spot, multiple endocrine hyperfunction, and polyostotic fibrous dysplasia. A somatic point mutation of Gsalpha protein leads to an increase in the Gsalpha-associated hormone activity in McCune-Albright syndrome. Because cyclic adenosine 3',5'-monophosphate stimulates the dopamine beta hydroxylase gene, an activating mutation of the Gsalpha protein may cause the hyperproduction of norepinephrine via dopamine. We report on a 9-year-old girl with McCune-Albright syndrome complicated by severe arterial hypertension. The urinary excretion of norepinephrine was 5- to 10-fold higher than in age-matched controls. Meta-iodobenzylguanidine scintigraphy and positron emission tomography/computed tomography (PET/CT) revealed no hot spots. These findings suggest that severe hypertension might be due to an activating mutation of Gsalpha protein in sympathetic ganglia. Because of the reported association of GNAS1 gene polymorphism with hypertension, our patient provides further evidence for a role of Gsalpha protein in hypertension.

Analysis of GNAS1 and PRKAR1A gene mutations in human cardiac myxomas not associated with multiple endocrine disorders

Cardiac myxomas are rare tumors that usually occur as sporadic lesions or,more rarely, in the familial form,mostly in the context of Carney complex (CNC). The molecular basis for the development of cardiac myxomas is unclear. However, somatic activating mutations in the GNAS1 gene (the gsp oncogene) are detected in the myocardium ofMcCune-Albright syndrome patients while germ-line mutations in the PRKAR1A gene are associated with CNC and familial myxomas. We investigated the presence of activating missense mutations in the GNAS1 gene as well as of inactivating mutations in PRKAR1A in 29 sporadically occurring cardiac myxomas. No gsp and no PRKAR1A mutations were found by direct sequencing of PCR products amplified from tumoral DNA. This is the first study including a large series of sporadic, isolated cardiac myxomas and showing that these cardiac neoplasms do not share the same mutations found in familial forms.

[Hyperthyroidism related to McCune-Albright syndrome: report of two cases and review of the literature]

INTRODUCTION

McCune-Albright syndrome is a sporadic disease clinicaly characterized by polyostotic fibrous dysplasia, "café-au-lait" cutaneous spots and hyperfunctional endocrinopathies, such as precocious puberty, hyperthyroidism, acromegaly and others. The biologic physiopathology of the disease is based on an activating mutation of the gene for the Gs protein which mediates the activation of adenyl cyclase and subsequent gland autonomous secretion. The thyroid gland is usually involved in this disease, being hyperthyroidism the second most common endocrinopathy seen after precocious puberty.

OBJECTIVE

Revision of the literature since 1937 to 1997, adding our casuistic and discussing the adequate treatment for the hyperthyroidism in the syndrome.

RESULTS

Among 85 cases identified with the syndrome, hyperthyroidism treatment was described in 26 of them. Fifteen were submitted to surgery (total thyroidectomy), 6 were submitted to iodotherapy and 5 were treated with antithyroid drugs (ATD - propylthiouracil, carbimazole or methimazole). In some cases, treatment association was done.

CONCLUSION

McCune-Albright syndrome is a rare disease, combining polyostotic fibrous dysplasia, "café-au-lait" cutaneous spots and hyperfunctional endocrinopathies. Cases with hyperthyroidism are treated initially clinically, but definitive ablation with surgery or radioiodine treatment is the most indicated option.

Fibrous dysplasia in a child with mitochondrial A8344G mutation

Myoclonic epilepsy associated with ragged red fibers (MERRF) syndrome is one of the major mitochondrial encephalomyopathies, with the involvement of various organs, which could be caused by mitochondrial A8344G DNA mutation. Monostotic fibrous dysplasia of bone, an asymptomatic developmental disorder, was reported to result from c-fos overexpression in osteogenic cells. Mitochondrial A8344G mutation has been shown to increase c-fos expression in a MERRF cybrid cell line. The authors describe a boy aged 10 years and 2 months with MERRF syndrome and A8344G mutation. Visual disturbance developed and deteriorated rapidly 5 months after the diagnosis of MERRF. A brain magnetic resonance imaging revealed optic nerve compression by sphenoid fibrous dysplasia, which was confirmed by histology. Fibrous dysplasia has never been mentioned in MERRF patients in the literature. This rare association may be because of underestimation, or it could be a coincidence. Care should be taken to explore the skeletal system in MERRF patients with focal symptoms.

Cellular and molecular basis of deiodinase-regulated thyroid hormone signaling

The iodothyronine deiodinases initiate or terminate thyroid hormone action and therefore are critical for the biological effects mediated by thyroid hormone. Over the years, research has focused on their role in preserving serum levels of the biologically active molecule T(3) during iodine deficiency. More recently, a fascinating new role of these enzymes has been unveiled. The activating deiodinase (D2) and the inactivating deiodinase (D3) can locally increase or decrease thyroid hormone signaling in a tissue- and temporal-specific fashion, independent of changes in thyroid hormone serum concentrations. This mechanism is particularly relevant because deiodinase expression can be modulated by a wide variety of endogenous signaling molecules such as sonic hedgehog, nuclear factor-kappaB, growth factors, bile acids, hypoxia-inducible factor-1alpha, as well as a growing number of xenobiotic substances. In light of these findings, it seems clear that deiodinases play a much broader role than once thought, with great ramifications for the control of thyroid hormone signaling during vertebrate development and metamorphosis, as well as injury response, tissue repair, hypothalamic function, and energy homeostasis in adults.

Age-dependent demise of GNAS-mutated skeletal stem cells and "normalization" of fibrous dysplasia of bone

We studied the role of somatic mosaicism in fibrous dysplasia of bone (FD) within the context of skeletal ("mesenchymal") stem cells by assessing the frequency of mutated colony forming unit-fibroblasts (CFU-Fs) from FD lesions, and in some cases, from unaffected sites, in a series of patients. There was a tight inverse correlation between the percentage mutant CFU-F versus age, suggesting demise of mutant stem cells caused by exuberant apoptosis noted in samples from young patients. In older patients, either partially or completely normal bone/marrow histology was observed. On in vivo transplantation, FD ossicles were generated only by cell strains in which mutant CFU-Fs were identified. Strains that lacked mutant CFU-F (but were mutation positive) failed to regenerate an FD ossicle. These data indicate that GNAS mutations are only pathogenic when in clonogenic skeletal stem cells. From these data, we have evolved the novel concept of "normalization" of FD. As a lesion ages, mutant stem cells fail to self-renew, and their progeny are consumed by apoptosis, whereas residual normal stem cells survive, self-renew, and enable formation of a normal structure. This suggests that activating GNAS mutations disrupt a pathway that is required for skeletal stem cell self-renewal.

Cyclic AMP inhibits the proliferation of thyroid carcinoma cell lines through regulation of CDK4 phosphorylation

How cyclic AMP (cAMP) could positively or negatively regulate G1 phase progression in different cell types or in cancer cells versus normal differentiated counterparts has remained an intriguing question for decades. At variance with the cAMP-dependent mitogenesis of normal thyroid epithelial cells, we show here that cAMP and cAMP-dependent protein kinase activation inhibit S-phase entry in four thyroid carcinoma cell lines that harbor a permanent activation of the Raf/ERK pathway by different oncogenes. Only in Ret/PTC1-positive TPC-1 cells did cAMP markedly inhibit the Raf/ERK cascade, leading to mTOR pathway inhibition, repression of cyclin D1 and p21 and p27 accumulation. p27 knockdown did not prevent the DNA synthesis inhibition. In the other cells, cAMP little affected these signaling cascades and levels of cyclins D or CDK inhibitors. However, cAMP differentially inhibited the pRb-kinase activity and T172-phosphorylation of CDK4 complexed to cyclin D1 or cyclin D3, whereas CDK-activating kinase activity remained unaffected. At variance with current conceptions, our studies in thyroid carcinoma cell lines and previously in normal thyrocytes identify the activating phosphorylation of CDK4 as a common target of opposite cell cycle regulations by cAMP, irrespective of its impact on classical mitogenic signaling cascades and expression of CDK4 regulatory partners.

Molecular markers and the pathogenesis of adrenocortical cancer

Adrenal tumors are common, with an estimated incidence of 7.3% in autopsy cases, while adrenocortical carcinomas (ACCs) are rare, with an estimated prevalence of 4-12 per million population. Because the prognoses for adrenocortical adenomas (ACAs) and ACCs are vastly different, it is important to be able to accurately differentiate the two tumor types. Advancement in the understanding of the pathophysiology of ACCs is essential for the development of more sensitive means of diagnosis and treatment, resulting in better clinical outcome. Adrenocortical tumors (ACTs) occur as a component of several hereditary tumor syndromes, which include the Li-Fraumeni syndrome, Beckwith-Wiedemann syndrome, multiple endocrine neoplasia 1, Carney complex, and congenital adrenal hyperplasia. The genes involved in these syndromes have also been shown to play a role in the pathogenesis of sporadic ACTs. The adrenocorticotropic hormone-cAMP-protein kinase A and Wnt pathways are also implicated in adrenocortical tumorigenesis. The aim of this review is to summarize the current knowledge on the molecular mechanisms involved in adrenocortical tumorigenesis, including results of comparative genomic hybridization, loss of heterozygosity, and microarray gene-expression profiling studies.

Inherited hypophosphatemic disorders in children and the evolving mechanisms of phosphate regulation

Phosphorous is essential for multiple cellular functions and constitutes an important mineral in bone. Hypophosphatemia in children leads to rickets resulting in abnormal growth and often skeletal deformities. Among various causes of low serum phosphorous are inherited disorders associated with increased urinary excretion of phosphate, including autosomal dominant hypophosphatemic rickets (ADHR), X-linked hypophosphatemia (XLH), autosomal recessive hypophosphatemia (ARHP), and hereditary hypophosphatemic rickets with hypercalciuria (HHRH). Recent genetic analyses and subsequent biochemical and animal studies have revealed several novel molecules that appear to play key roles in the regulation of renal phosphate handling. These include a protein with abundant expression in bone, fibroblast growth factor 23 (FGF23), which has proven to be a circulating hormone that inhibits tubular reabsorption of phosphate in the kidney. Two other bone-specific proteins, PHEX and dentin matrix protein 1 (DMP1), appear to be necessary for limiting the expression of fibroblast growth factor 23, thereby allowing sufficient renal conservation of phosphate. This review focuses on the clinical, biochemical, and genetic features of inherited hypophosphatemic disorders, and presents the current understanding of hormonal and molecular mechanisms that govern phosphorous homeostasis.

The role of type 1 and type 2 5'-deiodinase in the pathophysiology of the 3,5,3'-triiodothyronine toxicosis of McCune-Albright syndrome

CONTEXT

McCune-Albright syndrome (MAS) is caused by mutations in GNAS (most often R201C or R201H) leading to constitutive cAMP signaling and multiple endocrine dysfunctions, including morphological and functional thyroid involvement.

OBJECTIVE

The objective of the study was to characterize the clinical and molecular features of the MAS-associated thyroid disease in a large cohort of patients.

DESIGN

This was a retrospective analysis.

SETTING

The study was conducted at the National Institutes of Health Clinical Center.

PATIENTS

The study included 100 consecutive MAS patients.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURE

Functional and morphological evaluation of the thyroid was measured. Ex vivo experiments were performed on MAS thyroid samples to study the effects of the GNAS mutations on the 5'-deiodinases. Reconstitution experiments in HEK-293 cells were performed to study the effects of GNAS mutations on the type-2 5'-deiodinase.

RESULTS

Fifty-four patients had abnormal thyroid ultrasound findings. This group, compared with patients without abnormal findings, had higher T(3) to T(4) ratio, indicating an elevated 5'-deiodinase activity. Thyroid samples from MAS subjects, compared with normal tissue, showed a significant increase in both type 1 (D1) and type 2 (D2) 5'-deiodinase activity (D1 control 5.9 +/- 4.5 vs. MAS 41.7 +/- 26.8 fmol/min.mg, P < 0.001; D2 control 28.3 +/- 13.8 vs. MAS 153.1 +/- 43.7 fmol/min.mg, P < 0.001). Compared with cells transfected with the wild-type R201 allele, the basal transcriptional activity of the D2 promoter was significantly increased in both mutants (C and H) (R 10733 +/- 2855, vs. C 18548 +/- 4514, vs. H 19032 +/- 4410 RLU +/- SD, P < 0.001).

CONCLUSION

Thyroid pathology is a common occurrence in MAS. Consistent with the molecular etiology of the disease, the shift in T(3) to T(4) ratio is at least in part secondary to a cAMP-mediated intrathyroidal activation of D2 and to elevated D1 activity.

McCune-Albright syndrome

McCune-Albright syndrome (MAS) is classically defined by the clinical triad of fibrous dysplasia of bone (FD), café-au-lait skin spots, and precocious puberty (PP). It is a rare disease with estimated prevalence between 1/100,000 and 1/1,000,000. FD can involve a single or multiple skeletal sites and presents with a limp and/or pain, and, occasionally, a pathologic fracture. Scoliosis is common and may be progressive. In addition to PP (vaginal bleeding or spotting and development of breast tissue in girls, testicular and penile enlargement and precocious sexual behavior in boys), other hyperfunctioning endocrinopathies may be involved including hyperthyroidism, growth hormone excess, Cushing syndrome, and renal phosphate wasting. Café-au-lait spots usually appear in the neonatal period, but it is most often PP or FD that brings the child to medical attention. Renal involvement is seen in approximately 50% of the patients with MAS. The disease results from somatic mutations of the GNAS gene, specifically mutations in the cAMP regulating protein, G_s alpha. The extent of the disease is determined by the proliferation, migration and survival of the cell in which the mutation spontaneously occurs during embryonic development. Diagnosis of MAS is usually established on clinical grounds. Plain radiographs are often sufficient to make the diagnosis of FD and biopsy of FD lesions can confirm the diagnosis. The evaluation of patients with MAS should be guided by knowledge of the spectrum of tissues that may be involved, with specific testing for each. Genetic testing is possible, but is not routinely available. Genetic counseling, however, should be offered. Differential diagnoses include neurofibromatosis, osteofibrous dysplasia, non-ossifying fibromas, idiopathic central precocious puberty, and ovarian neoplasm. Treatment is dictated by the tissues affected, and the extent to which they are affected. Generally, some form of surgical intervention is recommended. Bisphosphonates are frequently used in the treatment of FD. Strengthening exercises are recommended to help maintaining the musculature around the FD bone and minimize the risk for fracture. Treatment of all endocrinopathies is required. Malignancies associated with MAS are distinctly rare occurrences. Malignant transformation of FD lesions occurs in probably less than 1% of the cases of MAS.

Apical involvement with fibrous dysplasia: implications for vision

PURPOSE

To describe the ophthalmic findings of fibrous dysplasia of the orbit.

METHODS

Prospective case series. Twenty-one patients with fibrous dysplasia with orbital involvement underwent a complete ophthalmic examination and orbital imaging by CT.

RESULTS

Four of the 21 patients had McCune-Albright syndrome and 1 had tuberous sclerosis. In 17 patients (81%), the disease was restricted to the craniofacial region. Facial distortion, proptosis, and eye dystopia were detected in 62% of the patients. Nasolacrimal duct obstruction and strabismus were detected in only 1 and 2 patients, respectively. Of the 34 orbits affected, the roof was affected in 67.6%. The floor was the least affected wall. For most orbits, the disease was seen in more than 1 wall, and in 9 orbits (26.5%) all 4 walls were involved. Twelve orbits (35.2%) showed cysts on CT within the affected bones. In 19 orbits (55.9%), the optic canal was circumferentially narrowed. Blindness was detected in only 1 patient who had undergone optic canal decompression.

CONCLUSIONS

The main consequences of orbital involvement in fibrous dysplasia are eye dystopia and proptosis. Apical involvement is a common feature. Optic canal narrowing does not necessarily induce vision loss. We believe that patients with apical involvement should be carefully followed and have their apices decompressed only when their vision is clearly deteriorating. Our data do not support prophylactic optic canal decompression as a therapeutic measure.

Pain in fibrous dysplasia of bone: age-related changes and the anatomical distribution of skeletal lesions

To determine the prevalence, distribution, age-related changes and treatment of pain in fibrous dysplasia, we studied 78 children and adults. Pain was common, more prevalent and intense in adults, sometimes requiring narcotic analgesia. It was often untreated, especially in children, and surprisingly severity did not correlate with skeletal disease burden.

INTRODUCTION

Pain is common in fibrous dysplasia (FD), but relatively unstudied. We studied a well-characterized population of patients with a spectrum of disease.

METHODS

Thirty-five children (16 male, 19 female, mean age 11.4 (range 5-18)) and 43 adults (15 male, 28 female, 23-62 yrs, mean age 40.3 (range 23-62)) were studied. Bone scans were used to identify the location and extent of disease. The Brief Pain Inventory was used to determine severity.

RESULTS

Pain at sites of FD was common, reported by 67% of the population, but more prevalent and severe in the adult group than the children (81% and 49%, respectively p < 0.005, severity 4.1/10, and 2.8/10, respectively, p < 0.01). Surprisingly, there was no correlation between pain severity and skeletal disease burden. Children were more likely than adults to be untreated for pain (44% vs. 26%).

CONCLUSIONS

Pain, which was sometimes severe, was common in subjects with FD. It was often un- or under-treated, especially in children. The prevalence and severity of pain was greater in the adult group, but unrelated to the burden of FD.

Restoration of ovulation after unilateral ovariectomy in a woman with McCune-Albright syndrome: a case report

INTRODUCTION

McCune-Albright syndrome (MAS) is characterized by peripheral precocious puberty, café-au-lait spots, and polyostotic fibrous dysplasia. This syndrome is due to a post-zygotic mutation of the GNAS1 gene with mosaic distribution and unilateral predominance. Clinical manifestations depend on the tissues carrying the mutation. We describe the ovarian function before and after unilateral ovariectomy in a woman with MAS and bilateral distribution of the GNAS1 gene mutation.

CASE REPORT

A 33-year-old patient, previously diagnosed as having MAS, presented irregular menstrual cycles (30-180 days) and monophasic temperature curves. Transvaginal ultrasound and blood tests were repeated at 3-day intervals over 3 months. Findings included a persistent quiescent left ovary, a persistent polycystic right ovary, constantly high estradiol-17beta (E2) levels, and very low FSH and LH levels. She also presented severe persistent pelvic pain. Because of unilateral ovarian activity, a unilateral right ovariectomy was performed as well as biopsy of the remaining left ovary. A GNAS1 gene mutation was identified in both ovaries. A regular monthly menstrual cycle was immediately restored. On day 3 of the menstrual cycle, E2 level was 30 pg/ml, FSH level was 7.5 mIU/ml, and LH level was 6.4 mIU/ml. On day 17, pelvic ultrasound showed one follicle of 25 mm in the left ovary. On day 21, the progesterone level was 13.1 ng/ml.

DISCUSSION

This is the first report of ovulation being restored following unilateral ovariectomy in an adult patient suffering from severe MAS with GNAS1 gene mutation identified in both ovaries.

Polyostotic fibrous dysplasia of the cervical spine: case report and review of the literature

BACKGROUND CONTEXT

Multiple lytic lesions of the spine usually represent metastatic or infectious disease processes.

PURPOSE

To describe an extremely rare presentation of an uncommon disease process.

STUDY DESIGN/SETTING

Case report/university hospital.

METHODS

We describe the management of a patient who presented with a pathological fracture of C3 and multiple lytic lesions of the cervical spine.

RESULTS

After reconstructive surgery, the final pathological diagnosis was fibrous dysplasia.

CONCLUSION

Fibrous dysplasia is rarely seen in the cervical spine and may mimic other pathological processes. The surgical and medical management of spinal fibrous dysplasia is described.

Onset, progression, and plateau of skeletal lesions in fibrous dysplasia and the relationship to functional outcome

Most lesions in FD and their attendant functional disability occur within the first decade; 90% of lesions are present by 15 years, and the median age when assistive devices are needed is 7 years. These findings have implications for prognosis and determining the timing and type of therapy.

INTRODUCTION

Fibrous dysplasia of bone (FD) is an uncommon skeletal disorder in which normal bone is replaced by abnormal fibro-osseous tissue. Variable amounts of skeletal involvement and disability occur. The age at which lesions are established, the pace at which the disease progresses, if (or when) the disease plateaus, and how these parameters relate to the onset of disability are unknown. To answer these questions, we performed a retrospective analysis of a group of subjects with FD.

MATERIALS AND METHODS

One hundred nine subjects with a spectrum of FD were studied for up to 32 years. Disease progression was assessed in serial (99)Tc-MDP bone scans by determining the location and extent of FD lesions using a validated bone scan scoring tool. Physical function and the need for ambulatory aids were assessed.

RESULTS

Ninety percent of the total body disease skeletal burden was established by age 15. Disease was established in a region-specific pattern; in the craniofacial region, 90% of the lesions were present by 3.4 yr, in the extremities, 90% were present by 13.7 yr, and in the axial skeleton, 90% were present by 15.5 yr. Twenty-five of 103 subjects eventually needed ambulatory aids. The median age at which assistance was needed was 7 yr (range, 1-43 yr). The median bone scan score for subjects needing assistance was 64.3 (range, 18.6-75) compared with 23.1 (range, 0.5-63.5) in the unassisted subjects (p < 0.0001). Among subjects needing assistance with ambulation, 92% showed this need by 17 yr.

CONCLUSIONS

The majority of skeletal lesions and the associated functional disability occur within the first decade of life. The implication is that the window of time for preventative therapies is narrow. Likewise, therapeutic interventions must be tailored to where the patient is in the natural history of the disease (i.e., progressive disease [young] versus established disease [older subjects]). These findings have implications for prognosis, the timing and type of therapy, and the development of trials of new therapies and their interpretation.

McCune-Albright syndrome and disorders due to activating mutations of GNAS1

It has been more than seven decades since Drs. Fuller Albright and Donovan McCune published the first reports on individuals with McCune-Albright syndrome (MAS). Since then, the classic triad of precocious puberty, café-aulait spots, and polyostotic bone dysplasia continues to define the syndrome. However, having gathered a better picture of the pathophysiology of MAS, the way this condition is understood has changed. Isolated activating mutations of the alpha subunit of the G protein (GNAS1) have been found in different tissues, including pituitary adenomas, thyroid adenomas, ovarian cysts, monostotic bone dysplasia, and the adrenal glands, to name a few. For this reason, we have added 'and disorders due to activating mutations of GNAS1' to the title of this review. We discuss here the clinical consequences of GNAS1 activating mutations in different body systems and organs, the diagnostic approach to MAS, and the current therapeutic recommendations.

A sensitive mutation-specific screening technique for GNAS1 mutations in cases of fibrous dysplasia: the first report of a codon 227 mutation in bone

AIMS

To report on the mutation-specific restriction enzyme digest (MSRED) method using paraffin-embedded tissue as a means of detecting GNAS1 mutations in fibrous dysplasia (FD), and to determine if any of the reported GNAS1 mutations in endocrine neoplasms, not previously documented in FD, can be found in FD.

METHODS AND RESULTS

Sixty-seven cases of extragnathic FD were analysed as two groups, 1997-2002 and 2003-06, chosen because tissue fixation and decalcification methods were more accurately recorded in the latter. MSRED revealed that between 2003 and 2006, 93% of 28 'in house' extragnathic cases harboured a GNAS1 mutation, compared with 75% of 32 cases before 2003. Fixation times of no more than 48 h and decalcification in ethylenediamine tetraacetic acid gave the best results. Of the 56 mutations detected (five gnathic, 51 extragnathic), 32 (57%) were R201H, 21 (38%) were R201C and three (5%) were Q227L. Two Q227L extragnathic cases had unusual clinical/radiological findings. No mutations were detected in osteofibrous dysplasia.

CONCLUSION

Detection of GNAS1 mutations by MSRED is a valuable adjunct to the histopathological diagnosis of FD. This is the first report of a Q227L mutation in FD, although it has been previously documented in pituitary adenoma.