Acromelic Dysplasia Research Articles

Weill-Marchesani syndrome: natural history and genotype-phenotype correlations from 18 news cases and review of literature

BackgroundWeill-Marchesani syndrome (WMS) belongs to the group of acromelic dysplasias, defined by short stature, brachydactyly and joint limitations. WMS is characterised by specific ophthalmological abnormalities, although cardiovascular defects have also...

TGF-β and BMP Signaling Pathways in Skeletal Dysplasia with Short and Tall Stature.

The transforming growth factor β (TGF-β) and bone morphogenetic protein (BMP) signaling pathways play a pivotal role in bone development and skeletal health. More than 30 different types of skeletal dysplasia are now known to be caused by pathogenic variants in genes that belong to the TGF-β superfamily and/or regulate TGF-β/BMP bioavailability. This review describes the latest advances in skeletal dysplasia that is due to impaired TGF-β/BMP signaling and results in short stature (acromelic dysplasia and cardiospondylocarpofacial syndrome) or tall stature (Marfan syndrome). We thoroughly describe the clinical features of the patients, the underlying genetic findings, and the pathomolecular mechanisms leading to disease, which have been investigated mainly using patient-derived skin fibroblasts and mouse models. Although no pharmacological treatment is yet available for skeletal dysplasia due to impaired TGF-β/BMP signaling, in recent years advances in the use of drugs targeting TGF-β have been made, and we also discuss these advances.

The fibrillinopathies: New insights with focus on the paradigm of opposing phenotypes for both FBN1 and FBN2.

Different pathogenic variants in the fibrillin‐1 gene (FBN1) cause Marfan syndrome and acromelic dysplasias. Whereas the musculoskeletal features of Marfan syndrome involve tall stature, arachnodactyly, joint hypermobility, and muscle hypoplasia, acromelic dysplasia patients present with short stature, brachydactyly, stiff joints, and hypermuscularity. Similarly, pathogenic variants in the fibrillin‐2 gene (FBN2) cause either a Marfanoid congenital contractural arachnodactyly or a FBN2‐related acromelic dysplasia that most prominently presents with brachydactyly. The phenotypic and molecular resemblances between both the FBN1 and FBN2‐related disorders suggest that reciprocal pathomechanistic lessons can be learned. In this review, we provide an updated overview and comparison of the phenotypic and mutational spectra of both the “tall” and “short” fibrillinopathies. The future parallel functional study of both FBN1/2‐related disorders will reveal new insights into how pathogenic fibrillin variants differently affect the fibrillin microfibril network and/or growth factor homeostasis in clinically opposite syndromes. This knowledge may eventually be translated into new therapeutic approaches by targeting or modulating the fibrillin microfibril network and/or the signaling pathways under its control.

Cooperative Mechanism of ADAMTS/ ADAMTSL and Fibrillin-1 in the Marfan Syndrome and Acromelic Dysplasias.

The term “fibrillinopathies” gathers various diseases with a wide spectrum of clinical features and severity but all share mutations in the fibrillin genes. The first described fibrillinopathy, Marfan syndrome (MFS), is a multisystem disease with a unique combination of skeletal, thoracic aortic aneurysm (TAA) and ocular features. The numerous FBN1 mutations identified in MFS are located all along the gene, leading to the same pathogenic mechanism. The geleophysic/acromicric dysplasias (GD/AD), characterized by short stature, short extremities, and joint limitation are described as “the mirror image” of MFS. Previously, in GD/AD patients, we identified heterozygous FBN1 mutations all affecting TGFβ-binding protein-like domain 5 (TB5). ADAMTS10, ADAMTS17 and, ADAMTSL2 are also involved in the pathogenic mechanism of acromelic dysplasia. More recently, in TAA patients, we identified mutations in THSD4, encoding ADAMTSL6, a protein belonging to the ADAMTSL family suggesting that ADAMTSL proteins are also involved in the Marfanoid spectrum. Together with human genetic data and generated knockout mouse models targeting the involved genes, we provide herein an overview of the role of fibrillin-1 in opposite phenotypes. Finally, we will decipher the potential biological cooperation of ADAMTS-fibrillin-1 involved in these opposite phenotypes.

Clinical and genetic characteristics of rare variants of acromelic skeletal dysplasias caused by mutations in the <i>FBN1</i> gene

BACKGROUND: Geleophysic dysplasia and acromicric dysplasia are rare hereditary diseases characterized by dwarfism and dysplastic skeletal features. In the literature, only a few cases of geleophysic dysplasia and acromicric dysplasia caused by mutations in the FBN1 gene are described.
 CLINICAL CASES: A description of the clinical and genetic characteristics of three female patients with acromelic dysplasias caused by three types of missense mutations in the FBN1 gene is presented. In two patients, on the basis of clinical manifestations and radiographic examination, acromicric dysplasia, and in one patient geleophysic dysplasia were diagnosed. It was shown that all identified mutations were localized in exons of the FBN1 gene encoding the amino acid sequence of the fifth domain, which has homology with transforming growth factor-beta.
 DISCUSSION: We have analyzed the clinical and genetic correlations to confirm the previously stated hypothesis about the occurrence of a severe phenotype of geleophysic dysplasia in patients with the c.5206T C mutation. This mutation is characterized by the replacement of cysteine by arginine in the position of the polypeptide chain leading to moderate clinical manifestations of acromicric dysplasia in patients with the c.5284 G A (p. Gly1762Ser). It was shown that the previously undescribed substitution c.5177G A (p.Gly1726Asp and another previously described mutation in this codon resulted in the replacement of glutamine with valine. This mutation causes the appearance of a less pronounced phenotype of AD.
 CONCLUSIONS: Based on the results of the examination of three Russian patients and analysis of clinical and radiographic parameters described in the literature, we reported that mutations in the FBN1 gene disrupted the amino acid sequence of the fifth like transforming growth factor-beta domain of fibrillin type 1. Importantly, these mutations are responsible for the occurrence of geleophysic dysplasia and acromicric dysplasia. However, the most severe clinical manifestations were observed in patients with mutations leading to the substitution of cysteine for arginine at the position of the polypeptide chain 1736. This may lead to affecting the transforming growth factor-beta signaling pathway.

Separation in genetic pathogenesis of mutations in FBN1-TB5 region between autosomal dominant acromelic dysplasia and Marfan syndrome.

Mutations in the transforming growth factor β-binding protein-like domain 5 (TB5) region of FBN1 can lead to autosomal acromelic dysplasia and Marfan syndrome, which are two diseases with apparently opposite phenotypes. We identified six patients with acromelic dysplasia carrying either the previously reported mutations c.5284G > A (p.Gly1762Ser) and c.5096A > G (p.Tyr1699Cys) or the novel mutation c.5260G > A (p.Gly1754Ser). A systematic review of patients with mutations in the FBN1-TB5 region showed that acromelic dysplasia is caused only by in-frame amino acid substitutions. In contrast, truncating mutations in the FBN1-TB5 have been reported only in Marfan syndrome. Acromelic dysplasia subtypes that share symptoms with Marfan syndrome are associated with FBN1-TB5 disulfide disruptions, which are also commonly found in Marfan syndrome. These results suggest that the type and location of mutations in the FBN1-TB5 region determine the clinical spectrum of fibrillinopathy.

Acromelic dysplasias: how rare musculoskeletal disorders reveal biological functions of extracellular matrix proteins.

Acromelic dysplasias are a group of rare musculoskeletal disorders that collectively present with short stature, pseudomuscular build, stiff joints, and tight skin. Acromelic dysplasias are caused by mutations in genes (FBN1, ADAMTSL2, ADAMTS10, ADAMTS17, LTBP2, and LTBP3) that encode secreted extracellular matrix proteins, and in SMAD4, an intracellular coregulator of transforming growth factor-β (TGF-β) signaling. The shared musculoskeletal presentations in acromelic dysplasias suggest that these proteins cooperate in a biological pathway, but also fulfill distinct roles in specific tissues that are affected in individual disorders of the acromelic dysplasia group. In addition, most of the affected proteins directly interact with fibrillin microfibrils in the extracellular matrix and have been linked to the regulation of TGF-β signaling. Together with recently developed knockout mouse models targeting the affected genes, novel insights into molecular mechanisms of how these proteins regulate musculoskeletal development and homeostasis have emerged. Here, we summarize the current knowledge highlighting pathogenic mechanisms of the different disorders that compose acromelic dysplasias and provide an overview of the emerging biological roles of the individual proteins that are compromised. Finally, we develop a conceptual model of how these proteins may interact and form an "acromelic dysplasia complex" on fibrillin microfibrils in connective tissues of the musculoskeletal system.

Are Fibrillin‐Notch Interactions Important in Development and Disease?

In humans, mutations in the gene for fibrillin‐1 (FBN1) cause both the Marfan syndrome as well as several types of acromelic dysplasias. Musculoskeletal features of the Marfan syndrome (long bone overgrowth and arachnodactyly, joint hypermobility, and a muscle wasting phenotype) are the opposite of those in acromelic dysplasias (short stature and brachydactyly, joint stiffness, and a hypermuscular build). How mutations in the same gene can result in opposite phenotypes is poorly understood. Mutations in FBN2 cause congenital contractural arachnodactyly, which features a mixture of related musculoskeletal features (muscle hypoplasia, contractures of the large and small joints and arachnodactyly).The fibrillins are multifunctional glycoproteins that polymerize into extracellular matrix microfibrils. Although we have associated fibrillin microfibril structure with the opposite musculoskeletal features of Marfan syndrome and acromelic dysplasias, we can only speculate that perturbations in growth factor signaling are involved. To begin to address this gap in our understanding, we hypothesize that direct interactions between fibrillin and cells coordinate growth factor signaling. Therefore, we searched for interactions between fibrillin and cellular receptors.Fibrillins, like Notch receptors and Notch ligands, are composed of multiple tandemly repeated cbEGF‐like domains. Each fibrillin contains 43 cbEGF‐like domains. What if Notch receptors or ligands also bind to fibrillins in the extracellular matrix? Our biochemical data imply that fibrillin interactions with Notch receptors or ligands are just as likely to occur in vivo as interactions between Notch receptors and known Notch transmembrane ligands. Human genetic evidence support significant roles for Notch signaling components in vascular and musculoskeletal diseases, tissues primarily affected in the fibrillinopathies.The current concept of Notch signaling is based strictly on cell‐cell communication. Our investigations have the potential to transform current understanding of context‐dependent Notch signaling by introducing the possibility that Notch signaling components also interact with fibrillin extracellular matrix.Support or Funding Informationgrants from the Shriners Hospitals for Children to Lynn Y. Sakai

Geleophysic dysplasia: one gene, different phenotypes

Geleophysic dysplasia (GD) is a rare multisystem disorder that affects bones, joints, heart, and skin. Mode of GD inheritance varies and can be autosomal recessive in case of ADAMTSL2 gene mutations and autosomal dominant in case of FBN1 and LTBP3 genes mutations. In the article we present an example of our own examination of two patients from different families, with different GD clinical picture, but with a common trait of pronounced dwarfism resistant to treatment with growth hormone. In the course of usual endocrine tests there has been no primary endocrine pathology detected. We have conducted genetic research in each family by method of exomic sequencing. In both patients we have identified de novo FBN1 heterozygous mutations p.Tyr1696Asp and p.Cys1748Ser. Both children had common clinical symptoms, such as pronounced dwarfism, distinctive facial features, short limbs, as well as joint contractures. However, in one patient we have identified heart pathology, while the other had tracheal stenosis, requiring tracheostomy. Patients with pronounced dwarfism, skeletal anomalies and other specific syndromes (such as tracheal stenosis and heart anomalies) have to undergo genetic testing in order to exclude syndromes of acromelic dysplasia.

A report of three families with FBN1-related acromelic dysplasias and review of literature for genotype-phenotype correlation in geleophysic dysplasia

Acromelic dysplasia is a heterogeneous group of rare skeletal dysplasias characterized by distal limb shortening. Weill-Marchesani syndrome (WMS), Geleophysic dysplasia (GD) and Acromicric dysplasia (AD) are clinically distinct entities within this group of disorders and are characterized by short stature, short hands, stiff joints, skin thickening, facial anomalies, normal intelligence and skeletal abnormalities. Mutations of the Fibrillin-1 (FBN1) gene have been reported to cause AD, GD and related phenotypes. We reported three families with acromelic short stature. FBN1 analysis showed that all affected individuals carry a heterozygous missense mutation c.5284G>A (p.Gly1762Ser) in exon 42 of the FBN1 gene. This mutation was previously reported to be associated with GD. We reviewed the literature and compared the clinical features of the patients with FBN1 mutations to those with A Distintegrin And Metalloproteinase with Thrombospondin repeats-like 2 gene (ADAMTSL2) mutations. We found that tip-toeing gait, long flat philtrum and thin upper upper lip were more consistently found in GD patients with ADAMTSL2 mutations than in those with FBN1 mutations. The results have shed some light on the phenotype-genotype correlation in this group of skeletal disorders. A large scale study involving multidisciplinary collaboration would be needed to consolidate our findings.

A chinese boy with geleophysic dysplasia caused by compound heterozygous mutations in ADAMTSL2

Geleophysic dysplasia, belonging to the group of acromelic dysplasia, is a rare genetic disease. Two genes, FBN1 and ADAMTSL2, were known to be linked to this disorder. The disorder presents as extreme short stature, short limbs, small hands and feet, stubby fingers and toes, joint stiffness, toe walking, skin thickening, progressive cardiac valvular thickening and characteristic facial features, including a round face with full cheeks. Here, we report the first Chinese case with geleophysic dysplasia type 1 based on clinical and genetic features. The boy was admitted because of severe physical growth retardation and mild motor retardation. Comprehensive medical evaluations were performed including metabolic studies, endocrine function examination, bone X-rays and echocardiography. Much delayed bone age and geleophysic dysplasia were found. Targeted next-generation sequencing was used to detect genetic mutations associated with skeletal dysplasia. Sanger sequencing was used to confirm the mutations in the patient. PCR amplification, cloing, and sequencing was used to determine the de novo mutation origin. Two compound heterozygous mutations were confirmed in the ADAMTSL2 gene of the patient. The c.340G > A (p.Glu114Lys) mutation was a de novo heterozygous mutation, and our results suggested that it was located on the paternal allele. While the c.234-2A > G inherited from his mother was a novel pathogenic heterozygous splicing mutation. Growth hormone deficiency had been observed in the patient. His growth velocity was improved by growth hormone supplementation. In conclusion, we have identified a novel splicing mutation of ADAMTSL2 carried by a Chinese boy with geleophysic dysplasia type 1. The patient was treated effectively with growth hormone supplementation.

Cervical artery dissection expands the cardiovascular phenotype in FBN1-related Weill-Marchesani syndrome.

Weill-Marchesani syndrome (WMS) is a rare form of acromelic dysplasia that is characterized by distinctive skeletal, ocular, and cardiovascular abnormalities. Previously described cardiac manifestations of WMS include aortic and pulmonary valve stenosis, mitral valve prolapse, mitral stenosis, and QTc prolongation. Autosomal dominant forms of WMS result from heterozygous pathogenic variants in FBN1, a gene with a well characterized role in the pathogenesis of thoracic aortic aneurysm (TAA) in the context of Marfan syndrome. In contrast, only one patient has been reported with aortic disease in WMS. Although the risk of aortic dissection from preceding TAA remains the leading cause of morbidity for individuals with Marfan syndrome, rare reports of arterial dissection in the peripheral vasculature have been described. Peripheral artery dissection has not been previously reported in other FBN1-related diseases. We describe a three generation family with FBN1-related WMS whose cardiovascular manifestations include TAA and cervical artery dissection, thus expanding the cardiovascular phenotype of WMS. Further research is required to quantify these risks and establish appropriate recommendations for cardiovascular imaging, medical management, and prophylactic surgical intervention in individuals with FBN1--related acromelic dysplasia.

New insights into the structure, assembly and biological roles of 10-12 nm connective tissue microfibrils from fibrillin-1 studies.

The 10-12 nm diameter microfibrils of the extracellular matrix (ECM) impart both structural and regulatory properties to load-bearing connective tissues. The main protein component is the calcium-dependent glycoprotein fibrillin, which assembles into microfibrils at the cell surface in a highly regulated process involving specific proteolysis, multimerization and glycosaminoglycan interactions. In higher metazoans, microfibrils act as a framework for elastin deposition and modification, resulting in the formation of elastic fibres, but they can also occur in elastin-free tissues where they perform structural roles. Fibrillin microfibrils are further engaged in a number of cell matrix interactions such as with integrins, bone morphogenetic proteins (BMPs) and the large latent complex of transforming growth factor-β (TGFβ). Fibrillin-1 (FBN1) mutations are associated with a range of heritable connective disorders, including Marfan syndrome (MFS) and the acromelic dysplasias, suggesting that the roles of 10-12 nm diameter microfibrils are pleiotropic. In recent years the use of molecular, cellular and whole-organism studies has revealed that the microfibril is not just a structural component of the ECM, but through its network of cell and matrix interactions it can exert profound regulatory effects on cell function. In this review we assess what is known about the molecular properties of fibrillin that enable it to assemble into the 10-12 nm diameter microfibril and perform such diverse roles.

A microfibril assembly assay identifies different mechanisms of dominance underlying Marfan syndrome, stiff skin syndrome and acromelic dysplasias.

Fibrillin-1 is the major component of the 10–12 nm diameter extracellular matrix microfibrils. The majority of mutations affecting the human fibrillin-1 gene, FBN1, result in Marfan syndrome (MFS), a common connective tissue disorder characterised by tall stature, ocular and cardiovascular defects. Recently, stiff skin syndrome (SSS) and a group of syndromes known collectively as the acromelic dysplasias, which typically result in short stature, skin thickening and joint stiffness, have been linked to FBN1 mutations that affect specific domains of the fibrillin-1 protein. Despite their apparent phenotypic differences, dysregulation of transforming growth factor β (TGFβ) is a common factor in all of these disorders. Using a newly developed assay to track the secretion and incorporation of full-length, GFP-tagged fibrillin-1 into the extracellular matrix, we investigated whether or not there were differences in the secretion and microfibril assembly profiles of fibrillin-1 variants containing substitutions associated with MFS, SSS or the acromelic dysplasias. We show that substitutions in fibrillin-1 domains TB4 and TB5 that cause SSS and the acromelic dysplasias do not prevent fibrillin-1 from being secreted or assembled into microfibrils, whereas MFS-associated substitutions in these domains result in a loss of recombinant protein in the culture medium and no association with microfibrils. These results suggest fundamental differences in the dominant pathogenic mechanisms underlying MFS, SSS and the acromelic dysplasias, which give rise to TGFβ dysregulation associated with these diseases.

Chondrodysplasias and TGFβ signaling.

Human chondrodysplasias are a group of conditions that affect the cartilage. This review is focused on the involvement of transforming growth factor-β signaling in a group of chondrodysplasias, entitled acromelic dysplasia, characterized by short stature, short hands and restricted joint mobility.

Dullard/Ctdnep1 regulates endochondral ossification via suppression of TGF-β signaling.

Transforming growth factor (TGF)-β signaling plays critical roles during skeletal development and its excessive signaling causes genetic diseases of connective tissues including Marfan syndrome and acromelic dysplasia. However, the mechanisms underlying prevention of excessive TGF-β signaling in skeletogenesis remain unclear. We previously reported that Dullard/Ctdnep1 encoding a small phosphatase is required for nephron maintenance after birth through suppression of bone morphogenetic protein (BMP) signaling. Unexpectedly, we found that Dullard is involved in suppression of TGF-β signaling during endochondral ossification. Conditional Dullard-deficient mice in the limb and sternum mesenchyme by Prx1-Cre displayed the impaired growth and ossification of skeletal elements leading to postnatal lethality. Dullard was expressed in early cartilage condensations and later in growth plate chondrocytes. The tibia growth plate of newborn Dullard mutant mice showed reduction of the proliferative and hypertrophic chondrocyte layers. The sternum showed deformity of cartilage primordia and delayed hypertrophy. Micromass culture experiments revealed that Dullard deficiency enhanced early cartilage condensation and differentiation, but suppressed mineralized hypertrophic chondrocyte differentiation, which was reversed by treatment with TGF-β type I receptor kinase blocker LY-364947. Dullard deficiency induced upregulation of protein levels of both phospho-Smad2/3 and total Smad2/3 in micromass cultures without increase of Smad2/3 mRNA levels, suggesting that Dullard may affect Smad2/3 protein stability. The phospho-Smad2/3 level was also upregulated in perichondrium and hypertrophic chondrocytes in Dullard-deficient embryos. Response to TGF-β signaling was enhanced in Dullard-deficient primary chondrocyte cultures at late, but not early, time point. Moreover, perinatal administration of LY-364947 ameliorated the sternum deformity in vivo. Thus, we identified Dullard as a new negative regulator of TGF-β signaling in endochondral ossification.

Novel Mutations in Geleophysic Dysplasia Type 1

Geleophysic dysplasia (GD) is a rare genetic disorder characterized by acromelic dysplasia. Geleophysic dysplasia type 1 (MIM 231050) is autosomal recessive and is caused by homozygous or compound heterozygous mutation in the ADAMTSL2 (a disintegrin and metalloproteinase with thrombosponding repeats-like 2) gene. Geleophysic dysplasia type 2 (MIM 614185) is autosomal dominant and is caused by heterozygous mutation in the fibrillin 1 (FBN1) gene. Here, we present the clinical and histopathologic findings in a child with GD with newly identified ADAMTSL2 mutations. The 1st mutation was probably a pathogenic one, c.[1934G>A] p.[Arg645His], located in exon 13; the 2nd, in intron 8, was probably changing a splice site. While the light and electron microscopic findings were similar to those previously described, hydrocephalus due to aqueductal stenosis might be a new associated finding in these patients. This child with these 2 novel mutations also had an aggressive clinical course with early-onset progressive cardiac valvular disease.

Similarity of geleophysic dysplasia and weill–marchesani syndrome

The acromelic dysplasias comprise short stature, hands and feet, and stiff joints. Three disorders are ascribed to this group, namely Weill-Marchesani syndrome, geleophysic dysplasia, and acromicric dysplasia, although similar in phenotype, can be distinguished clinically. Weill-Marchesani syndrome, on the basis of microspherophakia and ectopia lentis; geleophysic dysplasia by progressive cardiac valvular thickening, tracheal stenosis, and/or bronchopulmonary insufficiency, often leading to early death. Microspherophakia has not been reported previously in geleophysic dysplasia. Mutations in FBN1, ADAMTS10, or ADAMTS17 cause Weill-Marchesani syndrome by disrupting the microfibrillar environment, while geleophysic dysplasia is associated with enhanced TGF-β signaling mediated through mutations in FBN1 or ADAMTSL2. We studied a 35-year-old woman with geleophysic dysplasia, with short stature, small hands and feet, limitation of joint mobility, mild skin thickening, cardiac valvular disease, restrictive pulmonary disease, and microspherophakia. Sequencing of ADAMTSL2 demonstrated two changes: IVS8-2A>G consistent with a disease-causing mutation, and IVS14-7G>A with potential to generate a new splice acceptor site and result in aberrant mRNA processing. The unaffected mother carries only the IVS8-2A>G transition providing evidence that the two changes are in trans-configuration in our patient.

Missense mutations in FBN1 exons 41 and 42 cause Weill–Marchesani syndrome with thoracic aortic disease and Marfan syndrome

Mutations in FBN1 cause a range of overlapping but distinct conditions including Marfan syndrome (MFS), Weill-Marchesani syndrome (WMS), familial thoracic aortic aneurysms/dissections (FTAAD), acromicric dysplasia (AD), and geleophysic dysplasia (GD). Two forms of acromelic dysplasia, AD and GD, characterized by short stature, brachydactyly, reduced joint mobility, and characteristic facies, result from heterozygous missense mutations occurring in exons 41 and 42 of FBN1; missense mutations in these exons have not been reported to cause MFS or other syndromes. Here we report on probands with MFS and WMS who have heterozygous FBN1 missense mutations in exons 41 and 42, respectively. The proband with WMS has ectopia lentis, short stature, thickened pinnae, tight skin, striae atrophicae, reduced extension of the elbows, contractures of the fingers and toes, and brachydactyly and has a missense mutation in exon 42 of FBN1 (c.5242T>C; p.C1748R). He also experienced a previously unreported complication of WMS, an acute thoracic aortic dissection. The second proband displays classic characteristics of MFS, including ectopia lentis, skeletal features, and aortic root dilatation, and has a missense mutation in exon 41 of FBN1 (c.5084G>A; p.C1695Y). These phenotypes provide evidence that missense mutations in exons 41 and 42 of FBN1 lead to MFS and WMS in addition to AD and GD and also suggest that all individuals with pathogenic FBN1 mutations in these exons should be assessed for thoracic aortic disease and ectopia lentis. Further studies are necessary to elucidate the factors responsible for the different phenotypes associated with missense mutations in these exons of FBN1.

Marfan syndrome

Although historically Marfan syndrome (MFS) has always been considered as a condition caused by the deficiency of a structural extracellular matrix protein, fibrillin-1, the study of Marfan mouse models and Marfan-related conditions has shifted our current understanding to a pathogenic model that involves dysregulation of the cytokine-transforming growth factor beta (TGF-β) signaling. In this review, we focus on the impact of the revised MFS clinical diagnostic criteria. We discuss lessons that have been learned from molecular findings in relevant Marfan-related conditions, such as sporadic thoracic aortic aneurysm/dissection, stiff skin syndrome, acromelic dysplasias and Loeys-Dietz syndrome. We explore the latest insights into the role of the alternative TGF-β signaling pathways in MFS pathogenesis. Finally, we give an update on the current and future treatment strategies. The recent insights into the pathogenesis of MFS and related disorders have offered a prime example of translational medicine with immediate bridge between molecular findings and therapeutic options.