Phenotypic variability at the TGF-beta1 locus in Camurati-Engelmann disease

Roles of Chondroitin Sulfate Proteoglycans as Regulators of Skeletal Development

The extracellular matrix (ECM) is critically important for most cellular processes including differentiation, morphogenesis, growth, survival and regeneration. The interplay between cells and the ECM often involves bidirectional signaling between ECM components and small molecules, i.e., growth factors, morphogens, hormones, etc., that regulate critical life processes. The ECM provides biochemical and contextual information by binding, storing, and releasing the bioactive signaling molecules, and/or mechanical information that signals from the cell membrane integrins through the cytoskeleton to the nucleus, thereby influencing cell phenotypes. Using these dynamic, reciprocal processes, cells can also remodel and reshape the ECM by degrading and re-assembling it, thereby sculpting their environments. In this review, we summarize the role of chondroitin sulfate proteoglycans as regulators of cell and tissue development using the skeletal growth plate model, with an emphasis on use of naturally occurring, or created mutants to decipher the role of proteoglycan components in signaling paradigms.

Alteration of Bone Density, Microarchitecture, and Strength in Patients with Camurati-Engelmann Disease: Assessed by HR-pQCT

Camurati-Engelmann disease (CED) is a rare autosomal-dominant skeletal dysplasia caused by mutations in the transforming growth factor-β1 (TGFB1) gene. In this study, a retrospective review of patients with CED evaluated at Peking Union Medical College Hospital in Beijing, China, between November 30, 2000 and November 30, 2020 was conducted. Data including demographic data, manifestations, and examination results were characterized. Furthermore, bone geometry, density, and microarchitecture were assessed and bone strength was estimated by HR-pQCT. Results showed the median age at onset was 2.5 years. Common manifestations included pain in the lower limbs (94%, 17/18), abnormal gait (89%, 16/18), genu valgum (89%, 16/18), reduced subcutaneous fat (78%, 14/18), delayed puberty (73%, 8/11), muscle weakness (67%, 12/18), hearing loss (39%, 7/18), hepatosplenomegaly (39%, 7/18), exophthalmos or impaired vision or visual field defect (33%, 6/18), and anemia (33%, 7/18). Twenty-five percent (4/16) of patients had short stature. Serum level of alkaline phosphatase was elevated in 41% (7/17) of patients whereas beta-C-terminal telopeptide was elevated in 91% of patients (10/11). Among 12 patients, the Z-scores of two patients were greater than 2.5 at the femur neck and the Z-scores of five patients were lower than -2.5 at the femur neck and/or lumbar spine. HR-pQCT results showed lower volumetric BMD (vBMD), altered bone microstructure and lower estimated bone strength at the distal radius and tibia in patients with CED compared with controls. In addition, total volume bone mineral density and cortical volumetric bone mineral density at the radius were negatively correlated with age in patients with CED, but positively correlated with age in controls. In conclusion, the largest case series of CED with characterized clinical features in a Chinese population was reported here. In addition, HR-pQCT was used to investigate bone microstructure at the distal radius and tibia in nine patients with CED, and the alteration of bone density, microstructure, and strength was shown for the first time. © 2021 American Society for Bone and Mineral Research (ASBMR).

Aberrant activation of TGF-β1 induces high bone turnover via Rho GTPases-mediated cytoskeletal remodeling in Camurati-Engelmann disease

In the adult skeleton, the bone remodeling process involves a dynamic coordination between osteoblasts and osteoclasts, which is disrupted in diseases with high bone turnover rates and dysregulated transforming growth factor beta 1 (TGF-β1). However, little is known about how TGF-β1 signaling mediates bone resorption. Here, we described a pedigree with a heterozygous variant in TGF-β1 (R218C) that resulted in aberrant activation of TGF-β1 through an activating mechanism that caused Camurati-Engelmann disease (CED). We showed that CED patients have high levels of active Rho GTPases and the migration-related proteins Integrin β1 and Integrin β3 in their peripheral blood. HEK293T cells transfected with a plasmid encoding this mutant expressed high levels of TGF-β1 and active Rho GTPases. Furthermore, activation of Rho by TGF-β1 increased osteoclast formation and bone resorption, with increased migration of pre-osteoclasts, as well as cytoskeletal remodeling of pre-osteoclasts and mature osteoclasts. Importantly, pharmacological inhibition of Rho GTPases effectively rescued hyperactive TGF-β1-induced osteoclastogenesis in vitro. Overall, we propose that Rho GTPases mediate TGF-β1-induced osteoclastogenesis and suggest that Rho-TGF-β1 crosstalk is associated with high bone turnover in CED.

Improvement of Bone Health and Initiation of Puberty Development in Camurati-Engelmann Disease With Glucocorticoid and Losartan Treatment: A Case Report and Review of Literature

Camurati-Engelmann Disease (CED) is a rare sclerosing bone disease, sometimes associated delayed puberty. The treatment effect of glucocorticoid and angiotensin II receptor blocker (ARB) in bone health and puberty development remain unclear. We report a case of an 18-year-old girl who presented for a history of an enlarged head, pain of lower limbs, and no menstrual onset or breast development. Radiographs revealed thickening of skull and cortices in the diaphysis but sparse bone trabeculae in the spine and metaphysis. Sanger sequencing detected a mutation of c. 652C>T (p. R218C) in the gene TGFB1 and confirmed the diagnosis of CED. After treatment of a medium-to-small dosage of prednisone and losartan for 28 months, we observed improvement of bone mass in spine and hip and body fat mass and found initiation of puberty development. By a systemic review of current treatment strategies in patients with CED, we found that most cases reported relief of bone pain with treatment of glucocorticoid or ARB, but none has reported the outcome of hypogonadotropic hypogonadism. We propose that long-term use of glucocorticoid combined with ARB may inhibit the activation of TGFβ1 in CED, improve adipogenesis, and thus initiate puberty development and improve the bone mass in spine and hip.

Clinical characteristics and the influence of rs1800470 in patients with Camurati-Engelmann disease

BACKGROUND

Camurati-Engelmann disease (CED) is a sclerosing bone dysplasia caused by transforming growth factor β1 (TGFB1) gene variants.

OBJECTIVE

We aim to summarize the clinical characteristics and the efficacy of glucocorticoids in 14 individuals with CED, and explore the correlation between the phenotype and the SNP of rs1800470 (c.29C>T).

METHODS

Clinical, biochemical, radiological, and therapeutic data were collected from 14 patients. DNA was extracted for TGFB1 variants detection by Sanger sequencing.

RESULTS

The median onset and record age were 3.0 and 16.1 years, respectively. All patients manifested bone pain and decreased subcutaneous fat tissue. Inflammatory markers increased in over 60% of patients, and the median erythrocyte sedimentation rate (ESR) was 1.40 (0.50~3.67) of the upper limit of normal (ULN), and the median high sensitivity C reactive protein (hsCRP) was 1.71 (0.48~12.56) of ULN. There was a positive correlation between ESR and hsCRP (rs=0.806, p=0.003). Both ESR and hsCRP were negatively correlated with the levels of hemoglobin (HGB), calcium, and creatinine, but positively correlated with the level of alkaline phosphatase. Four known variants of TGFB1 were identified, including p.Tyr171Cys, p.Arg218Cys, p.Arg218His, and p.Cys225Arg. Moreover, 35.7% and 28.6% of them carried the heterozygous and homozygous SNP of c.29C>T, called C/T and T/T groups, respectively, but 35.7% of them were without c.29C>T (C/C group). The onset age, anthropometric data, percentages of different clinical manifestations, and biochemical parameters were comparable among the three groups. But there were increasing trends in levels of HGB and calcium and decreasing trends in ESR and hsCRP among C/C, C/T, and T/T groups in turn. Glucocorticoid improves the two inflammatory markers among CED patients.

CONCLUSION

The phenotype of CED is highly heterogeneous. There is no clear genotype-phenotype correlation, but it seems to have better trends of biochemical parameters in patients with CED carrying the T allele of rs1800470.

Relationship between bone disorders and stroke

Bone disorders are among the most uncommon causes of stroke, but they should be considered as stroke cause in particular clinical scenarios. On the other hand, osteoporosis/osteopenia and increased fracture risk are well documented post stroke complications. The relationship between stroke and bone health is complex. The current facts suggest that these two conditions share same risk factors, but also are risk factors for each other. However, the evidence shows more clear effect of stroke on the bone health, than in the opposite direction. This extensive review is aiming to fill the huge gap of evidence about this topic, and since bone pathology is extremely rare cause of cerebrovascular accident, although a complex connection between these two conditions definitely exists.

Genetic testing is useful in adults with limited phenotypes of genetic skeletal conditions

We show the value of genetic screening in 3 adults with limited phenotypes of three bone sclerosing genetic disease (GD): osteopetrosis (OPT), Camurati-Engelmann disease (CED) and pycnodysostosis.

INTRODUCTION

OPT, CED and pycnodysostosis are three rare bone diseases often diagnosed in childhood. However, some atypical phenotypes raise the problem of delayed diagnosis in adults. Genetic tests may then be useful to establish a formal diagnosis.

METHODS

We report 3 cases of adult patients with symptomatic or asymptomatic bone sclerosing lesions for whom the clinical, radiological and biological explorations were atypical and did not allow a formal diagnosis. These unusual descriptions led to the search for genetic mutations.

RESULTS

These 3 cases of limited phenotypes were associated with unknown or poorly described variants of 3 rare bone genetic diseases.

CONCLUSIONS

Genetic tests proved useful to establish the diagnosis and manage the condition of adults with rare bone sclerosing GD.

The Genetic Architecture of High Bone Mass

The phenotypic trait of high bone mass (HBM) is an excellent example of the nexus between common and rare disease genetics. HBM may arise from carriage of many 'high bone mineral density [BMD]'-associated alleles, and certainly the genetic architecture of individuals with HBM is enriched with high BMD variants identified through genome-wide association studies of BMD. HBM may also arise as a monogenic skeletal disorder, due to abnormalities in bone formation, bone resorption, and/or bone turnover. Individuals with monogenic disorders of HBM usually, though not invariably, have other skeletal abnormalities (such as mandible enlargement) and thus are best regarded as having a skeletal dysplasia rather than just isolated high BMD. A binary etiological division of HBM into polygenic vs. monogenic, however, would be excessively simplistic: the phenotype of individuals carrying rare variants of large effect can still be modified by their common variant polygenic background, and by the environment. HBM disorders-whether predominantly polygenic or monogenic in origin-are not only interesting clinically and genetically: they provide insights into bone processes that can be exploited therapeutically, with benefits both for individuals with these rare bone disorders and importantly for the many people affected by the commonest bone disease worldwide-i.e., osteoporosis. In this review we detail the genetic architecture of HBM; we provide a conceptual framework for considering HBM in the clinical context; and we discuss monogenic and polygenic causes of HBM with particular emphasis on anabolic causes of HBM.

Genetic Disruption of Anoctamin 5 in Mice Replicates Human Gnathodiaphyseal Dysplasia (GDD)

Gnathodiaphyseal dysplasia (GDD; OMIM#166260) is a rare skeletal disorder which is mainly characterized by cemento-osseous lesions in mandibles, bone fragility, bowing and diaphyseal sclerosis of tubular bones. GDD is caused by point mutations in Anoctamin-5 (ANO5); however, the disease mechanisms remain unclear. Here we generated Ano5-knockout (KO) mice using a CRISPR/Cas 9 approach to study loss of function aspects of GDD mutations. Homozygous Ano5 knockout mice (Ano5^-/-) replicate some typical traits of human GDD including massive jawbones, bowing tibia, sclerosis and cortical thickening of femoral and tibial diaphyses. Serum alkaline phosphatase (ALP) levels were elevated in Ano5^-/- mice as in GDD patients. Calvaria-derived Ano5^-/- osteoblast cultures show increased osteoblastogenesis, which is consistent with our previous in vitro observations. Bone matrix is hypermineralized, and the expression of bone formation-related factors is enhanced in Ano5^-/- mice, suggesting that the osteogenic anomaly arises from a genetic disruption of Ano5. We believe this new mouse model will shed more light on the development of skeletal abnormalities in GDD on a cellular and molecular level.

Effects of dietary calcium to available phosphorus ratios on bone metabolism and osteoclast activity of the OPG /RANK/RANKL signalling pathway in piglets

Hydroxyapatite, a mineral form of calcium (Ca) and phosphorus (P) that gives bones their rigidity, is the major and essential component of bones and teeth in the human and animal body. A suitable ratio of Ca and P is vital for bone growth. The aim of this study was to explore the effects of dietary calcium to available phosphorus ratios (Ca/AP) on bone metabolism and osteoclast activity of the osteoprotegerin (OPG)/receptor activator of nuclear factor kappa B ligand (RANKL) signalling pathway in piglets. At days 15 and 29, the piglets were assessed for growth performance, blood indicators, cytokines and the OPG/RANK/RANKL signalling pathway. Our results showed that piglets fed a dietary Ca/AP ratio of 2:1 increases growth performance and regulates blood indicators and cytokines (parathyroid hormone (PTH), calcitonin (CT), vitamin D₃ (VD₃ )_, insulin-like growth factor-1 (IGF-1), transforming growth factor-β (TGF-β), interleukin-1 (IL-1), interleukin-6 (IL-6), carboxyterminal propeptide of type I procollagen (PICP), tartrate-resistant acid phosphatase (TRACP), alkaline phosphatase (ALP) and osteocalcin (OCN) content). We also demonstrated that this ratio affects hormone secretion and further bone metabolism through the OPG/RANK/RANKL signalling pathway of osteoclasts. These results indicate that a suitable dietary Ca/AP ratio is vital for bone growth and reduce the incidence of bone diseases such as osteoporosis, providing a practical basis for the raising of piglets.

Observations on the Natural History of Camurati-Engelmann Disease

Camurati-Engelmann disease (OMIM 31300) is a rare cranio-tubular bone dysplasia characterized by osteosclerosis of the long bones and skull caused by dominantly-inherited mutations in the transforming growth factor beta 1 (TGFB1) gene. A wide variation in phenotype has been recognized, even within families carrying the same mutation. In addition, aspects of the natural history of the disorder, in particular whether it is always progressive or can remit spontaneously, remain uncertain. In a large kindred carrying a TGFB1 gene mutation (c.653G > A; p.R218H) we have attempted to clarify the extent of phenotypic variability and the natural history of the disease through detailed individual histories of symptoms, and skeletal imaging by both radiography and scintigraphy. Only one subject had the classical childhood onset with bone pain in the legs and gait disturbance. Eight subjects reported the onset of leg pain in their teenage years that, by their early 20s, had either resolved or persisted at a low level. Two of these eight later developed cranial nerve palsies. There was a wide variation in the radiographic appearance in adults, but disease extent and activity in long bones, as assessed by scintigraphy, was inversely correlated with age (p < 0.025). In younger subjects the radiographic and scintigraphic appearances were concordant, but in older subjects the scintigram could be quiescent despite florid radiographic changes. Sequential scintigrams in two subjects showed reduced activity in the later scan. One subject had suffered meningoencephalitis in early childhood that resulted in paresis of one arm. The affected arm showed markedly less disease involvement, implicating mechanical or growth factors in its etiology. Our data suggest that the natural history of Camurati-Engelmann disease can be benign, and that disease activity commonly attenuates in adulthood. Severe cases of childhood onset and/or with cranial nerve involvement, may occur only in a minority of mutation carriers. © 2019 American Society for Bone and Mineral Research.

Camurati-Engelmann Disease

Camurati-Engelmann disease or progressive diaphyseal dysplasia is a rare autosomal dominant sclerosing bone dysplasia. Mainly the skull and the diaphyses of the long tubular bones are affected. Clinically, the patients suffer from bone pain, easy fatigability, and decreased muscle mass and weakness in the proximal parts of the lower limbs resulting in gait disturbances. The disease-causing mutations are located within the TGFβ-1 gene and expected to or thought to disrupt the binding between TGFβ1 and its latency-associated peptide resulting in an increased signaling of the pathway and subsequently accelerated bone turnover. In preclinical studies, it was shown that targeting the type I receptor ameliorates the high bone turnover. In patients, treatment options are currently mostly limited to corticosteroids that may relieve the pain, and improve the muscle weakness and fatigue. In this review, the clinical and radiological characteristics as well as the molecular genetics of this condition are discussed.

The correlation of TGFβ1 gene polymorphisms with congenital heart disease susceptibility

OBJECTIVE

The aim of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in transforming growth factor beta 1 (TGFβ1) gene (rs1982073 and rs1800471) and congenital heart disease (CHD) susceptibility.

METHODS

Totally, 145 CHD patients and 140 healthy controls were enrolled in this case-control study. The case and control groups were matched in age and gender. Genotyping for TGFβ1 gene SNPs rs1982073 and rs1800471 was conducted via polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach. Chi-square test was used to analyze the association of TGFβ1 polymorphisms with CHD risk. The results were presented as odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The frequencies of the CT genotype and T allele of TGFβ1 gene SNP rs1982073 were significantly different between cases and controls (P < 0.05), revealing their associations with reduced susceptibility to CHD (OR = 0.521, 95%CI = 0.302-0.897; OR = 0.706, 95%CI = 0.507-0.983). Nevertheless, TGFβ1 gene SNP rs1800471 had no significant association with CHD susceptibility (P > 0.05).

CONCLUSION

TGFβ1 gene SNP rs1982073 might be correlated with CHD susceptibility, and the T allele might decrease the disease risk. However, TGFβ1 gene polymorphism rs1800471 was not related to CHD risk.

TGF-β Family Signaling in Mesenchymal Differentiation

Mesenchymal stem cells (MSCs) can differentiate into several lineages during development and also contribute to tissue homeostasis and regeneration, although the requirements for both may be distinct. MSC lineage commitment and progression in differentiation are regulated by members of the transforming growth factor-β (TGF-β) family. This review focuses on the roles of TGF-β family signaling in mesenchymal lineage commitment and differentiation into osteoblasts, chondrocytes, myoblasts, adipocytes, and tenocytes. We summarize the reported findings of cell culture studies, animal models, and interactions with other signaling pathways and highlight how aberrations in TGF-β family signaling can drive human disease by affecting mesenchymal differentiation.

Clinical characteristics and treatment outcomes in Camurati-Engelmann disease: A case series

BACKGROUND

Camurati-Engelmann disease is an extremely rare disease characterized by hyperostosis of multiple long bones. This condition is caused by heterozygous mutations in the TGFB1 gene.

METHODS

We describe the clinical and genetic characteristics of 4 Korean patients with this rare disease diagnosed at Asan Medical Center in Korea between June 2012 and May 2016, to increase awareness about this condition among general physicians and orthopedists. The presenting features, biochemical findings, radiographic and nuclear imaging findings, molecular analysis, and treatment outcomes of 4 patients were reviewed retrospectively.

RESULTS

Two patients had sporadic disease, whereas the other 2 were familial cases. The average age at symptom onset was 8.8 ± 5.5 (4-14) years. Symptoms included waddling gait or leg pain. Bone pain and easy fatigability were documented in all patients. Skeletal deformities such as osteoporosis, genu valgum, and severe scoliosis were observed. Visual and otologic manifestations presenting as exophthalmos, retinal detachment, and vestibulopathy were found in 3 patients. Skeletal survey showed diaphyseal expansion with diffuse cortical thickening of long bones in all patients. Bone scintigraphy images showed increased uptake of radioactive material in the calvarium and diaphysis of long bones. The mean erythrocyte sedimentation rate was 46.5 ± 22.2 (20-72) mm/h. Sequence analysis of TGFB1 revealed the previously reported mutations p.Arg218His, p.Arg218Cys, and p.Glu169Lys. Corticosteroid was effective in relieving pain, and losartan was used as maintenance therapy.

CONCLUSIONS

Our experience suggests that this rare condition can be suspected in patients with characteristic symptoms and skeletal findings. Considering the presence of effective medical treatment, efforts are needed to identify more cases.

Significant Improvement of Clinical Symptoms, Bone Lesions, and Bone Turnover after Long-Term Zoledronic Acid Treatment in Patients with a Severe Form of Camurati-Engelmann Disease

Camurati-Engelmann disease (CED) is an ultrarare autosomal dominant bone dysplasia. Cortical thickening of the diaphyses of the long bones with narrowing of the medullary cavity are associated with bone pain, waddling gait, muscular weakness, easy fatigability, and a marfanoid body habitus. There is no specific treatment for CED. Nonsteroidal anti-inflammatory drugs or glucocorticoids are ineffective in improving bone lesions. A family with a mild to severe form of CED is described. Two patients received long-term bisphosphonate treatment: the 19-year-old female proband was treated with zoledronic acid for 2.2 years; the 4-year-old male proband was treated with neridronic acid for 16 months and with zoledronic acid for an additional 18 months. In both probands, zoledronic acid treatment significantly improved the clinical symptoms, bone lesions, ambulation, and body habitus. Before treatment, both probands showed a marked increase in serum levels of osteocalcin, procollagen type I N-terminal propeptide, and cross-linked carboxyterminal telopeptide of type I collagen, reflecting an increased bone turnover. Bone marker levels returned to their normal values during treatment. Zoledronic acid treatment may be an important therapeutic option in patients with severe CED. Biochemical markers of bone turnover could be considered as surrogate indexes of CED activity.

Camurati-Engelmann disease-a rare cause of tetany identified on bone scintigraphy: A case report

RATIONALE

Camurati-Engelmann disease (i.e., progressive diaphyseal dysplasia) is an extremely rare autosomal dominant bone disorder. The most common clinical manifestations were chronic skeletal pain, waddling gait, muscular weakness.

PATIENT CONCERNS

We described that a 27-year-old male with a 1-year history of intermittent tetany was referred for bone scintigraphy. The whole body bone scan images showed abnormal increased uptake of the tracer in the long bones of the upper and lower extremities as well as in the skull.

DIAGNOSES

Combined the family history, the findings of the images and the genetic study, the diagnosis of Camurati-Engelmann disease was confirmed.

INTERVENTIONS AND OUTCOMES

The patient responded well to the treatment of calcium gluconate.

LESSONS

Bone scintigraphy would be helpful in the diagnosis and assessing the severity of Camurati-Engelmann disease.

Association between transforming growth factor-beta 1 gene single nucleotide polymorphisms and knee osteoarthritis susceptibility in a Chinese Han population

Objective

To investigate associations between single polymorphisms (SNPs) rs1800469 and rs1982073 in the transforming growth factor-β1 gene (TGF-β1) and knee osteoarthritis (OA) susceptibility in a Chinese Han population.

Methods

TGF-β1 rs1800469 and rs1982073 were genotyped in patients with knee OA and age- and sex-matched OA-free controls from a Chinese Han population. The association was further analyzed according to gender and age.

Results

A total of 765 patients with knee OA and 780 controls were included. CT and CT + CC genotypes of rs1982073, and variant C, were associated with a significantly increased risk of knee OA. Stratification analysis showed that the association between the OA risk and rs1982073 CT heterozygotes compared with TT homozygotes was stronger in females and those aged >65 years. In contrast, CT, TT, and CT + TT genotypes of rs1800469 were not significantly associated with the risk of knee OA, even after further stratification analysis for gender and age.

Conclusions

The TGF-β1 rs1982073 T to C change and the variant C genotype may contribute to knee OA risk in the Chinese Han population.

The Good the Bad and the Ugly of Glycosaminoglycans in Tissue Engineering Applications

High sulfation, low cost, and the status of heparin as an already FDA- and EMA- approved product, mean that its inclusion in tissue engineering (TE) strategies is becoming increasingly popular. However, the use of heparin may represent a naïve approach. This is because tissue formation is a highly orchestrated process, involving the temporal expression of numerous growth factors and complex signaling networks. While heparin may enhance the retention and activity of certain growth factors under particular conditions, its binding 'promiscuity' means that it may also inhibit other factors that, for example, play an important role in tissue maintenance and repair. Within this review we focus on articular cartilage, highlighting the complexities and highly regulated processes that are involved in its formation, and the challenges that exist in trying to effectively engineer this tissue. Here we discuss the opportunities that glycosaminoglycans (GAGs) may provide in advancing this important area of regenerative medicine, placing emphasis on the need to move away from the common use of heparin, and instead focus research towards the utility of specific GAG preparations that are able to modulate the activity of growth factors in a more controlled and defined manner, with less off-target effects.

A Rare Sporadic Case of Camurati-Engelmann Disease With Jaw Involvement

Camurati-Engelmann disease (CED), or progressive diaphyseal dysplasia, is an uncommon bone dysplasia that is inherited in an autosomal-dominant pattern. The disease mainly affects the diaphyses of the long bones but can induce sclerotic changes to the facial skeleton and skull base. The diagnosis of CED is based on clinical and radiologic features. This article presents the clinical and radiologic characteristics of the jaws as visualized on cone-beam computed tomograms of a 46-year-old woman diagnosed with CED.

Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia

Gnathodiaphyseal dysplasia (GDD; MIM#166260) is an autosomal dominant syndrome with characteristic cemento-osseous lesions of jawbones, bone fragility, and diaphyseal sclerosis of tubular bones. To date, only five mutations in the proposed calcium-activated chloride channel ANO5/TMEM16E gene have been identified. In this study, we describe two families and two singular patients with three new mutations. One Caucasian family with seven affected members exhibited frequent bone fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family with two affected members suffered from cementoma and purulent osteomyelitis (p.Cys360Tyr). In addition, two different novel mutations (p.Gly518Glu and p.Arg215Gly) were identified in sporadic patients without family history. In vitro studies overexpressing GDD mutations (p.Cys356Tyr and p.Cys360Tyr) showed significantly reduced ANO5 protein. It appears that all GDD mutations known so far locate in an extracellular domain following the first transmembrane domain or in the 4^th putative transmembrane domain. Both wild-type and mutant ANO5 protein localize to the endoplasmic reticulum. After Ano5 gene knock-down with shRNA in MC3T3-E1 osteoblast precursors we saw elevated expression of osteoblast-related genes such as Col1a1, osteocalcin, osterix and Runx2 as well as increased mineral nodule formation in differentiating cells. Our data suggest that ANO5 plays a role in osteoblast differentiation.

Mild Camurati‑Engelamann disease presenting with exophthalmos as the first and only manifestation: A case report

Camurati-Engelmann disease (CED; MIM 131300), or progressive diaphyseal dysplasia, is a rare autosomal dominant bone disease, which is caused by mutations in the transforming growth factor‑β1 (TGFβ1) gene on chromosome 19q13.1‑13.3. Extremely variable penetrance has been reported to be associated with CED, the most common features of which are limb pain, waddling gait and muscle weakness. The present study reported on a consanguineous Chinese family with one affected individual that initially presented with exophthalmos, which has not previously been reported as an initial manifestation of CED. The proband was a 22-year-old woman that presented with progressive proptosis. Except for increased serum levels of alkaline phosphatase and C‑terminal telopeptide of type I collagen, no other biochemical abnormalities were detected. Whole‑body radiological and bone scintigraphic investigations revealed that hyperostosis and sclerosis predominantly affected the cranial bones, including the skull base, and only mildly affected the long bones. A heterozygous mutation involving a G to A transition at the cDNA position +653 of TGFβ1 was detected in the patient only, but not in her family members, by automated DNA sequencing using an ABI DNA sequencer (Model 377). Based on the clinical, biochemical, radiological and genetic findings, a diagnosis of CED was confirmed. Considering the phenotypic variability associated with CED and the unique manifestations of the patient described in the present study, CED should be taken into account regarding the differential diagnosis of exophthalmos.

TGF-β and BMP signaling in osteoblast, skeletal development, and bone formation, homeostasis and disease

Transforming growth factor-beta (TGF-β) and bone morphogenic protein (BMP) signaling has fundamental roles in both embryonic skeletal development and postnatal bone homeostasis. TGF-βs and BMPs, acting on a tetrameric receptor complex, transduce signals to both the canonical Smad-dependent signaling pathway (that is, TGF-β/BMP ligands, receptors, and Smads) and the non-canonical-Smad-independent signaling pathway (that is, p38 mitogen-activated protein kinase/p38 MAPK) to regulate mesenchymal stem cell differentiation during skeletal development, bone formation and bone homeostasis. Both the Smad and p38 MAPK signaling pathways converge at transcription factors, for example, Runx2 to promote osteoblast differentiation and chondrocyte differentiation from mesenchymal precursor cells. TGF-β and BMP signaling is controlled by multiple factors, including the ubiquitin–proteasome system, epigenetic factors, and microRNA. Dysregulated TGF-β and BMP signaling result in a number of bone disorders in humans. Knockout or mutation of TGF-β and BMP signaling-related genes in mice leads to bone abnormalities of varying severity, which enable a better understanding of TGF-β/BMP signaling in bone and the signaling networks underlying osteoblast differentiation and bone formation. There is also crosstalk between TGF-β/BMP signaling and several critical cytokines’ signaling pathways (for example, Wnt, Hedgehog, Notch, PTHrP, and FGF) to coordinate osteogenesis, skeletal development, and bone homeostasis. This review summarizes the recent advances in our understanding of TGF-β/BMP signaling in osteoblast differentiation, chondrocyte differentiation, skeletal development, cartilage formation, bone formation, bone homeostasis, and related human bone diseases caused by the disruption of TGF-β/BMP signaling.

BMP signalling in skeletal development, disease and repair

Since the identification in 1988 of bone morphogenetic protein 2 (BMP2) as a potent inducer of bone and cartilage formation, BMP superfamily signalling has become one of the most heavily investigated topics in vertebrate skeletal biology. Whereas a large part of this research has focused on the roles of BMP2, BMP4 and BMP7 in the formation and repair of endochondral bone, a large number of BMP superfamily molecules have now been implicated in almost all aspects of bone, cartilage and joint biology. As modulating BMP signalling is currently a major therapeutic target, our rapidly expanding knowledge of how BMP superfamily signalling affects most tissue types of the skeletal system creates enormous potential to translate basic research findings into successful clinical therapies that improve bone mass or quality, ameliorate diseases of skeletal overgrowth, and repair damage to bone and joints. This Review examines the genetic evidence implicating BMP superfamily signalling in vertebrate bone and joint development, discusses a selection of human skeletal disorders associated with altered BMP signalling and summarizes the status of modulating the BMP pathway as a therapeutic target for skeletal trauma and disease.

A single nucleotide polymorphism in the TGF-β1 gene (rs1982073 C>T) may contribute to increased risks of bone fracture, osteoporosis, and osteoarthritis: a meta-analysis

Genetic factors have been shown to be of great importance for the pathogenesis of bone diseases, such as fracture, osteoporosis (OP), and osteoarthritis (OA). However, published studies on the correlations of transforming growth factor-β1 (TGF-β1) gene polymorphisms with bone diseases have been hampered by small sample sizes or inconclusive findings. We hence aimed at examining the relationships between a single nucleotide polymorphism in the TGF-β1 gene (rs1982073 C>T) with bone fracture, OP, and OA risks in this meta-analysis. A systematic electronic search of literature was conducted to identify all published studies in English or Chinese on the association between the TGF-β1 gene and fracture, OP, or OA risks. Data were abstracted independently by two reviewers. To investigate the strength of this relationship, crude odds ratios with 95 % confidence intervals were used. An updated meta-analysis based on nine independent case-control studies were chosen (patients with fracture, OP, or OA = 1569; healthy controls = 1638). Results identified a higher frequency of rs1982073 C>T in patients with fracture, OP, or OA than in healthy controls. Ethnicity and genotyping method-stratified analysis under both models implied that the rs1982073 C>T polymorphism was positively correlated with the risk of fracture, OP, and OA among Asians under detection via the non-PCR-RFLP method. Disease-stratified results yielded that rs1982073 C>T may increase the risk of fracture, OP, and OA under the allele model, but was only significantly related to OP under the dominant model. According to the sample size-stratified analysis, subjects with the rs1982073 C>T polymorphism in the allele model were more likely to develop the three bone diseases in both the small and large sample size groups, and only in the large sample size under the dominant model. Our findings show that TGF-β1 rs1982073 C>T has a modest effect in increasing susceptibility to bone fracture, OP, and OA.

A comprehensive network and pathway analysis of human deafness genes

OBJECTIVE

To perform comprehensive network and pathway analyses of the genes known to cause genetic hearing loss.

STUDY DESIGN

In silico analysis of deafness genes using ingenuity pathway analysis (IPA).

METHODS

Genes relevant for hearing and deafness were identified through PubMed literature searches and the Hereditary Hearing Loss Homepage. The genes were assembled into 3 groups: 63 genes that cause nonsyndromic deafness, 107 genes that cause nonsyndromic or syndromic sensorineural deafness, and 112 genes associated with otic capsule development and malformations. Each group of genes was analyzed using IPA to discover the most interconnected, that is, "nodal" molecules, within the most statistically significant networks (p < 10).

RESULTS

The number of networks that met our criterion for significance was 1 for Group 1 and 2 for Groups 2 and 3. Nodal molecules of these networks were as follows: transforming growth factor beta1 (TGFB1) for Group 1, MAPK3/MAPK1 MAP kinase (ERK 1/2) and the G protein coupled receptors (GPCR) for Group 2, and TGFB1 and hepatocyte nuclear factor 4 alpha (HNF4A) for Group 3. The nodal molecules included not only those known to be associated with deafness (GPCR), or with predisposition to otosclerosis (TGFB1), but also novel genes that have not been described in the cochlea (HNF4A) and signaling kinases (ERK 1/2).

CONCLUSION

A number of molecules that are likely to be key mediators of genetic hearing loss were identified through three different network and pathway analyses. The molecules included new candidate genes for deafness. Therapies targeting these molecules may be useful to treat deafness.

Regulation of TGFβ and related signals by precursor processing

Secreted cytokines of the TGFβ family are found in all multicellular organisms and implicated in regulating fundamental cell behaviors such as proliferation, differentiation, migration and survival. Signal transduction involves complexes of specific type I and II receptor kinases that induce the nuclear translocation of Smad transcription factors to regulate target genes. Ligands of the BMP and Nodal subgroups act at a distance to specify distinct cell fates in a concentration-dependent manner. These signaling gradients are shaped by multiple factors, including proteases of the proprotein convertase (PC) family that hydrolyze one or several peptide bonds between an N-terminal prodomain and the C-terminal domain that forms the mature ligand. This review summarizes information on the proteolytic processing of TGFβ and related precursors, and its spatiotemporal regulation by PCs during development and various diseases, including cancer. Available evidence suggests that the unmasking of receptor binding epitopes of TGFβ is only one (and in some cases a non-essential) function of precursor processing. Future studies should consider the impact of proteolytic maturation on protein localization, trafficking and turnover in cells and in the extracellular space.

Hypothalamic amenorrhea in a Camurati-Engelmann disease--a case report

OBJECTIVE

A case report of a patient diagnosed with Camurati-Engelmann Disease (CED) in association with the functional hypothalamic amenorrhea disturbances. CED is a very rare genetically determined disorder classified as a type of bone dysplasia.

DESIGN

Case report.

SETTING

Department of Gynecological Endocrinology, 3rd grade Medical University Hospital.

PATIENT

Twenty-one years old female patient with CED admitted to the hospital because of primary amenorrhea. Her history revealed skeletal deformities and hearing impairment.

METHODS

Clinical examination, ultrasound, laboratory evaluations (including serum gonadotropins (FSH, LH) at basal state and after stimulation with gonadotropin-releasing hormone, serum basal estradiol) radiological studies (X-ray of the head, the lumbar spine and lower extremities; a computed tomography of the head), G-banding karyotype, polymerase chain reaction and DNA sequencing. Hormonal serum evaluations were made using an enzyme-linked immunosorbent assay. The exon 4 of the transforming growth factor beta 1 gene was amplified by a polymerase chain reaction and the product was directly sequenced.

RESULTS

The hormonal analysis was characteristic for the hypogonadotropic hypogonadism. Radiological and molecular analyses confirmed CED diagnosis.

CONCLUSIONS

The hypothalamic amenorrhea in a patient with CED may be explained as a consequence of fat hypotrophy and very low body mass index. Therefore, impairment within hypothalamic-pituitary axis in patients with CED should be treated with special attention.

Transforming growth factor-β1 gene mutations and phenotypes in pediatric patients with Camurati‑Engelmann disease

The aim of the present study was to investigate the clinical characteristics and major causative gene in pediatric patients with Camurati‑Engelmann disease (CED). Biochemical and radiographic examinations, bone scintigraphy and genetic analyses were performed in two affected males and their parents. The two patients experienced waddling gait, muscular weakness and growth developmental delay. X-ray radiography revealed typical fusiform thickening of the diaphyseal portions of the long bones. The abnormal uptake of tracer Tc-99m was visualized in the skull and both sides of the upper humeri, ulnas, radii, femurs and tibias using bone scintigraphy. Serum levels of the bone formation marker procollagen type I N-terminal propeptide (PINP) and the bone resorption marker β‑isomerized C-terminal cross-linked telopeptide of type I collagen (β-CTX) in the 6-year-old patient were significantly increased compared with the normal value range, while only the β-CTX levels were elevated in the 16-year-old patient. A heterozygous missense mutation p.Arg218Cys in exon 4 of the transforming growth factor β1 (TGFβ1) gene was detected in the two patients, while their parents had normal wild‑type genotypes. In conclusion, the p.Arg218Cys mutation was shown to contribute to the clinical phenotypes in two pediatric patients with CED. The results of this study suggest that abnormal bone turnover marker levels, typical radiological findings and mutations in the TGFβ1 gene are three important factors in the diagnosis of sporadic CED cases.

Friend or foe: high bone mineral density on routine bone density scanning, a review of causes and management

A finding of high BMD on routine DXA scanning is not infrequent and most commonly reflects degenerative disease. However, BMD increases may also arise secondary to a range of underlying disorders affecting the skeleton. Although low BMD increases fracture risk, the converse may not hold for high BMD, since elevated BMD may occur in conditions where fracture risk is increased, unaffected or reduced. Here we outline a classification for the causes of raised BMD, based on identification of focal or generalized BMD changes, and discuss an approach to guide appropriate investigation by clinicians after careful interpretation of DXA scan findings within the context of the clinical history. We will also review the mild skeletal dysplasia associated with the currently unexplained high bone mass phenotype and discuss recent advances in osteoporosis therapies arising from improved understanding of rare inherited high BMD disorders.

TGF-β and BMP signaling in osteoblast differentiation and bone formation

Transforming growth factor-beta (TGF-β)/bone morphogenic protein (BMP) signaling is involved in a vast majority of cellular processes and is fundamentally important throughout life. TGF-β/BMPs have widely recognized roles in bone formation during mammalian development and exhibit versatile regulatory functions in the body. Signaling transduction by TGF-β/BMPs is specifically through both canonical Smad-dependent pathways (TGF-β/BMP ligands, receptors and Smads) and non-canonical Smad-independent signaling pathway (e.g. p38 mitogen-activated protein kinase pathway, MAPK). Following TGF-β/BMP induction, both the Smad and p38 MAPK pathways converge at the Runx2 gene to control mesenchymal precursor cell differentiation. The coordinated activity of Runx2 and TGF-β/BMP-activated Smads is critical for formation of the skeleton. Recent advances in molecular and genetic studies using gene targeting in mice enable a better understanding of TGF-β/BMP signaling in bone and in the signaling networks underlying osteoblast differentiation and bone formation. This review summarizes the recent advances in our understanding of TGF-β/BMP signaling in bone from studies of genetic mouse models and human diseases caused by the disruption of TGF-β/BMP signaling. This review also highlights the different modes of cross-talk between TGF-β/BMP signaling and the signaling pathways of MAPK, Wnt, Hedgehog, Notch, and FGF in osteoblast differentiation and bone formation.

Camurati-Engelmann disease: unique variant featuring a novel mutation in TGFβ1 encoding transforming growth factor beta 1 and a missense change in TNFSF11 encoding RANK ligand

We report a 32-year-old man and his 59-year-old mother with a unique and extensive variant of Camurati-Engelmann disease (CED) featuring histopathological changes of osteomalacia and alterations within TGFβ1 and TNFSF11 encoding TGFβ1 and RANKL, respectively. He suffered leg pain and weakness since childhood and reportedly grew until his late 20s, reaching 7 feet in height. He had deafness, perforated nasal septum, torus palatinus, disproportionately long limbs with knock-knees, low muscle mass, and pseudoclubbing. Radiographs revealed generalized skeletal abnormalities, including wide bones and cortical and trabecular bone thickening in keeping with CED, except that long bone ends were also affected. Lumbar spine and hip BMD Z-scores were + 7.7 and + 4.4, respectively. Biochemical markers of bone turnover were elevated. Hypocalciuria accompanied low serum 25-hydroxyvitamin D (25[OH]D) levels. Pituitary hypogonadism and low serum insulin-like growth factor (IGF)-1 were present. Karyotype was normal. Despite vitamin D repletion, iliac crest histology revealed severe osteomalacia. Exon 1 of TNFRSF11A (RANK), exons 2, 3, and 4 of LRP5, and all coding exons and adjacent mRNA splice junctions of TNFRSF11B (OPG), SQSTM1 (sequestosome 1), and TNSALP (tissue nonspecific alkaline phosphatase) were intact. His asymptomatic and less dysmorphic 5'11″ mother, also with low serum 25(OH)D, had milder clinical, radiological, biochemical, and histopathological findings. Both individuals were heterozygous for a novel 12-bp duplication (c.27_38dup, p.L10_L13dup) in exon 1 of TGFβ1, predicting four additional leucine residues in the latency-associated-peptide segment of TGFβ1, consistent with CED. The son was also homozygous for a single base transversion in TNFSF11, predicting a nonconservative amino acid change (c.107C > G, p.Pro36Arg) in the intracellular domain of RANKL that was heterozygous in his nonconsanguineous parents. This TNFSF11 variant was not found in the SNP Database, nor in published TNFSF11 association studies, but it occurred in four of the 134 TNFSF11 alleles (3.0%) we tested randomly among individuals without CED. Perhaps the unique phenotype of this CED family is conditioned by altered RANKL activity.

Skeletal dysplasias associated with mild myopathy-a clinical and molecular review

Musculoskeletal system is a complex assembly of tissues which acts as scaffold for the body and enables locomotion. It is often overlooked that different components of this system may biomechanically interact and affect each other. Skeletal dysplasias are diseases predominantly affecting the development of the osseous skeleton. However, in some cases skeletal dysplasia patients are referred to neuromuscular clinics prior to the correct skeletal diagnosis. The muscular complications seen in these cases are usually mild and may stem directly from the muscle defect and/or from the altered interactions between the individual components of the musculoskeletal system. A correct early diagnosis may enable better management of the patients and a better quality of life. This paper attempts to summarise the different components of the musculoskeletal system which are affected in skeletal dysplasias and lists several interesting examples of such diseases in order to enable better understanding of the complexity of human musculoskeletal system.

Incomplete penetrance and variable expressivity: is there a microRNA connection?

Incomplete penetrance and variable expressivity are non-Mendelian phenomena resulting in the lack of correlation between genotype and phenotype. Not withstanding the diversity in mechanisms, differential expression of homologous alleles within cells manifests as variations in penetrance and expressivity of mutations between individuals of the same genotype. These phenomena are seen most often in dominantly inherited diseases, implying that they are sensitive to concentration of the gene product. In this framework and the advances in understanding the role of microRNA (miRNA) in fine-tuning gene expression at translational level, we propose miRNA-mediated regulation as a mechanism for incomplete penetrance and variable expressivity. The presence of miRNA binding sites at 3' UTR, co-expression of target gene-miRNA pairs for genes showing incomplete penetrance and variable expressivity derived from available data lend support to our hypothesis. Single nucleotide polymorphisms in the miRNA target site facilitate the implied differential targeting of the transcripts from homologous alleles.

The first Korean case of Camurati-Engelmann disease (progressive diaphyseal dysplasia) confirmed by TGFB1 gene mutation analysis

Camurati-Engelmann disease (CED) is an autosomal dominant progressive diaphyseal dysplasia caused by mutations in the transforming growth factor-beta1 (TGFB1) gene. We report the first Korean family with an affected mother and son who were diagnosed with CED. The proband is a 19-yr-old male with a history of abnormal gait since the age of 2. He also suffered from proximal muscle weakness, pain in the extremities, and easy fatigability. Skeletal radiographs of the long bones revealed cortical, periosteal, and endosteal thickenings, predominantly affecting the diaphyses of the upper and lower extremities. No other bony abnormalities were noted in the skull and spine and no remarkable findings were seen on laboratory tests. The patient's mother had a long-standing history of mild limb pain. Under the impression of CED on radiographic studies, we performed mutation analysis. A heterozygous G to A transition at cDNA position +653 in exon 4 of the TGFB1 gene (R218H) was detected in the patient and his mother.

A common biosynthetic pathway governs the dimerization and secretion of inhibin and related transforming growth factor beta (TGFbeta) ligands

The assembly and secretion of transforming growth factor beta superfamily ligands is dependent upon non-covalent interactions between their pro- and mature domains. Despite the importance of this interaction, little is known regarding the underlying regulatory mechanisms. In this study, the binding interface between the pro- and mature domains of the inhibin alpha-subunit was characterized using in vitro mutagenesis. Three hydrophobic residues near the N terminus of the prodomain (Leu(30), Phe(37), Leu(41)) were identified that, when mutated to alanine, disrupted heterodimer assembly and secretion. It is postulated that these residues mediate dimerization by interacting non-covalently with hydrophobic residues (Phe(271), Ile(280), Pro(283), Leu(338), and Val(340)) on the outer convex surface of the mature alpha-subunit. Homology modeling indicated that these mature residues are located at the interface between two beta-sheets of the alpha-subunit and that their side chains form a hydrophobic packing core. Mutation of these residues likely disturbs the conformation of this region, thereby disrupting non-covalent interactions with the prodomain. A similar hydrophobic interface was identified spanning the pro- and mature domains of the inhibin beta(A)-subunit. Mutation of key residues, including Ile(62), Leu(66), Phe(329), and Pro(341), across this interface was disruptive for the production of both inhibin A and activin A. In addition, mutation of Ile(62) and Leu(66) in the beta(A)-propeptide reduced its ability to bind, or inhibit the activity of, activin A. Conservation of the identified hydrophobic motifs in the pro- and mature domains of other transforming growth factor beta superfamily ligands suggests that we have identified a common biosynthetic pathway governing dimer assembly.

A novel mutation of TGF beta1 in a Chinese family with Camurati-Engelmann disease

Camurati-Engelmann disease (CED) [OMIM 131300] is a rare autosomal dominant disorder characterized by bone pain and osteosclerosis affecting the diaphysis of long bones. It has been previously reported that CED is caused by mutations of the transforming growth factor beta 1 (TGF beta1) gene on chromosome 19q13.1-q13.3. Until now, seven mutations (LLL12-13ins, Y81H, R156C, R218C, R218H, H222D, C225R) in Australian, French, Belgian, Japanese, and European families have been reported and these data showed that there was no correlation between the nature of the mutations and the variability of the clinical manifestations. In this study, we found a Chinese family with CED and observed some intra-familial clinical variability and symptoms that became more severe with the age. A new TGF beta1 mutation (E169K) in exon 2 was identified in the Chinese family using polymerase chain reaction, direct sequencing analysis of PCR products and single-strand conformation polymorphism analysis. This mutation has not been previously reported in other countries in the world.

TGF-beta and osteoarthritis

OBJECTIVE

Cartilage damage is a major problem in osteoarthritis (OA). Growth factors like transforming growth factor-beta (TGF-beta) have great potential in cartilage repair. In this review, we will focus on the potential therapeutic intervention in OA with TGF-beta, application of the growth factor TGF-beta in cartilage repair and on the side effects of TGF-beta treatment that could occur.

METHODS

This review summarizes peer-reviewed articles published in the PubMed database before November 2006. In addition, this review is supplemented with recent data of our own group on the use of TGF-beta as a cartilage reparative factor in OA.

RESULTS

TGF-beta is crucial for cartilage maintenance and lack there of results in OA-like changes. Moreover, TGF-beta supplementation can enhance cartilage repair and is therefore a potential therapeutic tool. However, application of TGF-beta supplementation provides problems in other tissues of the joint and results in fibrosis and osteophyte formation. This can potentially be overcome by local inhibition of TGF-beta at sites of unwanted side-effects or by blocking downstream mediators of TGF-beta that are important for the induction of fibrosis or osteophyte formation.

CONCLUSION

Current understanding of TGF-beta suggests that it essential for cartilage integrity and that it is a powerful tool to prevent or repair cartilage damage. The side-effects that occur with TGF-beta supplementation can be overcome by local inhibition of TGF-beta itself or downstream mediators.

Camurati-Engelmann disease in conjunction with hypogonadism

OBJECTIVE

To report a case of Camurati-Engelmann disease (CED) in conjunction with hypogonadism, an association that has not been previously described.

METHODS

We present the clinical, laboratory, and histopathologic features of our case. In addition, we review the molecular genetics of CED.

RESULTS

CED is a rare autosomal dominant disorder of the skeleton, characterized by bilaterally symmetric, progressive dysplasia of the bones. The typical features of this disorder are hyperostotic and sclerotic changes in the bones, primarily of the extremities. Our patient, a 49-year-old male resident of a nursing home, presented with muscle weakness, waddling gait, bone pain, and increased fatigability, usual features of CED (which had been formally diagnosed when he was 8 years old). He also had hyponatremia, hyperkalemia, and almost undetectable serum testosterone. The gene responsible for CED has been mapped to the same locus as the gene for the synthesis of transforming growth factor (TGF-b 1). Mutations in the TGF b 1 gene have been identified in patients with CED. TGF-b 1 also has an important role in reproductive function, both during embryogenesis and in adulthood. It has predominant effects on steroidogenesis as well as spermatogenesis. We discuss the hormonal and histopathologic changes in our patient and postulate that the association of CED with hypogonadism could be attributable to the impaired regulation of gonadal growth and steroidogenesis, in which TGF-b 1 has an important role.

CONCLUSION

We propose that the association of CED with hypogonadism could be explained on the basis of a common underlying mutation in the TGF b 1 gene, leading to accumulation of excessive TGF-b 1.

Transforming growth factor-beta1 differentially mediates fibronectin and inflammatory cytokine expression in kidney tubular cells

Transforming growth factor-beta(1) (TGF-beta(1)) is not only an important fibrogenic but also immunomodulatory cytokine in the human kidney. We have recently demonstrated that TGF-beta(1) induces interleukin-8 (IL-8), macrophage chemoattractant protein-1 (MCP-1), and fibronectin production in renal proximal tubular (HK-2) cells. However, the unique dependence of IL-8, MCP-1, and fibronectin on TGF-beta(1) expression is unknown. The TGF-beta(1) gene was effectively silenced in HK-2 cells using small-interference (si) RNA. Basal secretion of IL-8 and MCP-1 decreased (both P < 0.05) but, paradoxically, fibronectin increased (P < 0.05) in TGF-beta(1)-silenced cells compared with cells transfected with nonspecific siRNA. Significant increases were observed in mRNA for the TGF-beta(2) (P < 0.05), TGF-beta(3) (P < 0.05) isoforms and pSmad2 (P < 0.05), which were reflected in protein expression. Concurrent exposure to pan-specific TGF-beta antibody reversed the observed increase in fibronectin expression, suggesting that TGF-beta(2) and TGF-beta(3) isoforms mediate the increased fibronectin expression in TGF-beta(1)-silenced cells. An increase in the DNA binding activity of activator protein-1 (AP-1; P < 0.05) was also observed in TGF-beta(1)-silenced cells. In contrast, nuclear factor-kappaB (NF-kappaB) DNA binding activity was significantly decreased (P < 0.0005). These studies demonstrate that TGF-beta(1) is a key regulator of IL-8 and MCP-1, whereas fibronectin expression is regulated by a complex interaction between the TGF-beta isoforms in the HK-2 proximal tubular cell line. Decreased expression of TGF-beta(1) reduces chemokine production in association with reduced NF-kappaB DNA binding activity, suggesting that immunomodulatory pathways in the kidney are specifically dependent on TGF-beta(1). Conversely, decreased expression of TGF-beta(1) results in increased TGF-beta(2), TGF-beta(3), AP-1, and pSmad2 that potentially mediates the observed increase in fibronectin.

Mutations of TGFbeta signaling molecules in human disease

The transforming growth factor beta (TGFbeta) signaling pathway regulates several biological processes including cellular proliferation, differentiation, apoptosis, migration, and extracellular matrix deposition. Ligand and receptor family members signal through two main Smad signaling branches, TGFbeta/activin to Smad2/3 (Sma and MAD-related proteins) and bone morphogenetic protein (BMP) to Smad1/5. At the molecular level, TGFbeta acts by modifying cytoskeletal organization and ultimately regulating expression of specific target genes. Germline disruption of TGFbeta signaling leads to several types of hereditary congenital malformation or dysfunction of the skeletal, muscular and/or cardiovascular systems, and to cancer predisposition syndromes. In this review, the molecular etiology of TGFbeta-associated disorders is examined, together with a discussion of clinical overlap between syndromes and possible biological explanations underlying the variable penetrance and expressivity of clinical characteristics. Increasing our understanding of the molecular etiology underlying genotype-phenotype correlations will ultimately provide a molecular-based approach that should result in better prognostic tools, smart therapeutics and individualized disease management, not only for these rare syndromes, but for more generalized disorders of the cardiovascular and musculoskeletal systems and cancer. The clinical consequence of TGFbeta signaling mutations appears to depend on environmental factors and on the basal levels of ongoing signaling transduction networks specific to each individual. In this respect, genetic background might be a central factor in determining disease outcome and treatment strategy for TGFbeta-associated diseases.

Camurati-Engelmann disease (progressive diaphyseal dysplasia) in a Moroccan family

We report on a 46-year-old mother of Moroccan origin, suffering mainly from painful, swollen legs, and her 26-year-old son who had experienced intense pain in his legs, without fever, for approximately 3 years. They did not have dysmorphic features or abnormal gaits. Radiographic studies of the mother revealed diaphyseal sclerosis of the tibia and spondylosis of the thoracal and lumbar vertebrae. The son had sclerosis of the diaphyses of the metacarpalia of the left hand, the femur and the fibula. The other parts of the skeleton were normal. Several osteosclerotic/hyperostotic disorders, such as melorheostosis (present mostly in sporadic cases and affecting lower extremities) and van Buchem's disease (autosomal recessive and commonly affecting the mandible) were considered as a diagnosis in the proposita. However, similar symptoms in the son of the proposita suggested an autosomal dominant inheritance pattern. This brought us to the diagnosis of progressive diaphyseal dysplasia (PDD) or Camurati-Engelmann disease (CED), an autosomal dominant disorder characterized by limb pain, reduced muscle mass, weakness, a waddling gait, progressive periosteal and endosteal sclerosis of the diaphyses of the long bones and sclerosis of the skull base. Mutations in the transforming growth factor (TGF)-beta1 gene on chromosome 19q13.1 have been reported to cause this disorder. The diagnosis of PDD/CED in this family was confirmed at the molecular level by detection of a C-to-T transition at position 466, leading to an arginine-to-cysteine amino acid change (position 156) in exon 2 of the transforming growth factor-beta1 (TGFB1) gene.

Maintenance of chondroitin sulfation balance by chondroitin-4-sulfotransferase 1 is required for chondrocyte development and growth factor signaling during cartilage morphogenesis

Glycosaminoglycans (GAGs) such as heparan sulfate and chondroitin sulfate are polysaccharide chains that are attached to core proteins to form proteoglycans. The biosynthesis of GAGs is a multistep process that includes the attachment of sulfate groups to specific positions of the polysaccharide chains by sulfotransferases. Heparan-sulfate and heparan sulfate-sulfotransferases play important roles in growth factor signaling and animal development. However, the biological importance of chondroitin sulfation during mammalian development and growth factor signaling is poorly understood. We show that a gene trap mutation in the BMP-induced chondroitin-4-sulfotransferase 1 (C4st1) gene (also called carbohydrate sulfotransferase 11 - Chst11), which encodes an enzyme specific for the transfer of sulfate groups to the 4-O-position in chondroitin, causes severe chondrodysplasia characterized by a disorganized cartilage growth plate as well as specific alterations in the orientation of chondrocyte columns. This phenotype is associated with a chondroitin sulfation imbalance, mislocalization of chondroitin sulfate in the growth plate and an imbalance of apoptotic signals. Analysis of several growth factor signaling pathways that are important in cartilage growth plate development showed that the C4st1(gt/gt) mutation led to strong upregulation of TGFbeta signaling with concomitant downregulation of BMP signaling, while Indian hedgehog (Ihh) signaling was unaffected. These results show that chondroitin 4-O-sulfation by C4st1 is required for proper chondroitin sulfate localization, modulation of distinct signaling pathways and cartilage growth plate morphogenesis. Our study demonstrates an important biological role of differential chondroitin sulfation in mammalian development.

Camurati-Engelmann disease: review of the clinical, radiological, and molecular data of 24 families and implications for diagnosis and treatment

Camurati-Engelmann disease (CED) is a rare autosomal dominant type of bone dysplasia. This review is based on the unpublished and detailed clinical, radiological, and molecular findings in 14 CED families, comprising 41 patients, combined with data from 10 other previously reported CED families. For all 100 cases, molecular evidence for CED was available, as a mutation was detected in TGFB1, the gene encoding transforming growth factor (TGF) beta1. Pain in the extremities was the most common clinical symptom, present in 68% of the patients. A waddling gait (48%), easy fatigability (44%), and muscle weakness (39%) were other important features. Radiological symptoms were not fully penetrant, with 94% of the patients showing the typical long bone involvement. A large percentage of the patients also showed involvement of the skull (54%) and pelvis (63%). The review provides an overview of possible treatments, diagnostic guidelines, and considerations for prenatal testing. The detailed description of such a large set of CED patients will be of value in establishing the correct diagnosis, genetic counselling, and treatment.

[Genetics of osteoporosis]

Osteoporosis is a multifactorial disease involving genetic component and several environmental factors. Some rare diseases that are associated with osteoporosis such as Lobstein disease or the "pseudoglial osteoporosis" syndrom are monogenetic. Nevertheless common osteoporosis is a polygenic affection resulting from the interaction between the polymorphism of different genes and the environmental factors. The genetic component of osteoporosis encompasses roughly 60 to 70% of bone mineral density, whereas the effect on fracture risk seems lower because of the importance of other environmental factors as falls. Many polymorphisms of candidate genes involved in the regulation of bone mass have been correlated to bone density. It is likely that many genes participate to the regulation of bone density although the existence of a major gene is highly suspected. Moreover linkage analysis after genome-wide search in populations with severe osteoporosis has focused on some regions of interest (QTL) on the chromosomes. This will allow to localize one or more specific genes. The current genetic studies on different populations affected by osteoporosis or not will be useful in order to better predict the fracture risk in association with bone density and biochemical markers of bone turnover. Moreover, this will lead to the development of new treatments of osfeoporosis and will help to adapt the therapy for individual patients.

Marked phenotypic variability in progressive diaphyseal dysplasia (Camurati-Engelmann disease): report of a four-generation pedigree, identification of a mutation in TGFB1, and review

Progressive diaphyseal dysplasia (PDD) (Camurati-Engelmann disease) is an autosomal dominant craniotubular dysplasia characterized by hyperostosis and sclerosis of the diaphyses of the long bones and the skull. Mutations in transforming growth factor beta-1 (TGFB1) were recently found in patients with PDD. We report on a four-generation pedigree with seven individuals affected by PDD, linkage and mutational analysis results, and review the literature. This pedigree demonstrates the autosomal dominant inheritance pattern, remarkable variation in expressivity, and reduced penetrance. The most severely affected individual had progression of mild skull hyperostosis to severe skull thickening and cranial nerve compression over 30 years. His carrier father remained asymptomatic into his ninth decade and had no radiographic hyperostosis or sclerosis of the bones. Symptomatic relatives presented with lower limb pain and weakness. They were initially diagnosed with a variety of other conditions. Two of the symptomatic individuals were treated successfully with prednisone. We genotyped 7 markers from chromosome region 19q13.1-13.3 in 15 relatives and confirmed linkage to this region in this family. We screened the TGFB1 gene for mutations and identified a missense mutation resulting in an R218H substitution in the affected individuals, the asymptomatic obligate carrier, and another unaffected relative. We genotyped the family for seven known TGFB1 polymorphisms and a novel TAAA tetranucleotide repeat in intron 1. These polymorphisms did not appear to account for the variability in disease severity in this family. Our review illustrates how the disorder can significantly compromise health. Cranial involvement, which occurs in 61% of patients, can be severe, entrapping cranial nerves or causing increased intracranial pressure. Therapy with corticosteroids should be attempted in all symptomatic patients.

Inherited disorders of cytokines

PURPOSE OF REVIEW

Cytokines are soluble mediators involved in the development or function of the immune system. This paper reviews the literature on childhood-onset inherited disorders associated with impaired cytokine-mediated immunity.

RECENT FINDINGS

Cytokine-mediated immunity defects can be classified into seven different groups: defects in the interleukin (IL)-7 receptor (IL7RA), in the common cytokine receptor gamma chain (gammac) of the IL-2, -4, -7, -15, and -21, and in Jak3 (JAK3) downstream of the gamma chain; mutation in the IL-2 receptor alpha (IL-2RA) and defective expression of the IL-2Rbeta chain; mutations in the gene encoding for a chemokine receptor, CXCR4; mutations in five genes involved in the IL-12/23-interferon-gamma axis (IL12B, IL12RB1, IFNGR1, IFNGR2, STAT1); mutations in three genes involved in the nuclear factor-kappaB signaling pathway (IRAK4, NEMO, IkappaBA); mutations in the tumor necrosis factor receptor signaling pathway (TNFRSF1A); and mutations in the transforming growth factor-1 gene (TGFB1).

SUMMARY

Genetic cytokine-mediated immunity defects are associated with a highly heterogeneous group of clinical features, ranging from susceptibility to infections to developmental defects. This heterogeneity highlights the diversity and pleiotropy of cytokines. It is likely that many more cytokine defects and their responsive pathways will be discovered in the coming years, expanding further the heterogeneity associated with this group of childhood-onset illnesses.