Phenotypic Heterogeneity of Marfan-Like Connective Tissue Disorders Associated With Mutations in the Transforming Growth Factor-.BETA. Receptor Genes

Predictors of low bone density and fracture risk in Loeys-Dietz syndrome

PURPOSE

Loeys-Dietz syndrome (LDS) is a connective tissue disorder affecting multiple organ systems, including bone.

METHODS

We defined the bone phenotype and clinical predictors of low bone density and fracture risk in 77 patients with LDS type 1 to type 5.

RESULTS

Patients with LDS had dual-energy x-ray absorptiometry (DXA) Z-scores significantly < 0, and 50% of children and 9% of adults had Z-scores < -2. Sixty percent of patients had ≥1 fracture, and 24% of patients with spinal x-rays scans showed spinal compression fractures. Lower body mass index, asthma, male sex and eosinophilic gastrointestinal disease were correlated with lower DXA Z-scores. The count of 5 LDS-associated skeletal features (scoliosis, pes planus, arachnodactyly, spondylolisthesis, and camptodactyly) in patients with LDS was correlated with DXA Z-score. Adults with ≥1 skeletal features had DXA Z-scores significantly < 0, and children with >2 features had DXA Z-score significantly < -2. Bone turnover markers suggest accelerated bone resorption. Data from 5 patients treated with bisphosphonates suggest a beneficial effect.

CONCLUSION

All LDS types are associated with reduced bone density and increased risk of fracture, which may be due to increased bone resorption. Clinical features can predict a subgroup of patients at highest risk of low bone density and fracture risk.

Loeys-Dietz and Shprintzen-Goldberg syndromes: analysis of TGF-β-opathies with craniofacial manifestations using an innovative multimodality method

BACKGROUND

Elevated transforming growth factor-beta (TGF-β) signalling has been implicated in the pathogenesis of Loeys-Dietz syndrome (LDS) and Shprintzen-Goldberg syndrome (SGS). In this study, we provide a qualitative and quantitative analysis of the craniofacial and functional features among the LDS subtypes and SGS.

METHODS

We explore the variability within and across a cohort of 44 patients through deep clinical phenotyping, three-dimensional (3D) facial photo surface analysis, cephalometric and geometric morphometric analyses of cone-beam CT scans.

RESULTS

The most common craniofacial features detected in this cohort include mandibular retrognathism (84%), flat midface projection (84%), abnormal eye shape (73%), low-set ears (73%), abnormal nose (66%) and lip shape (64%), hypertelorism (41%) and a relatively high prevalence of nystagmus/strabismus (43%), temporomandibular joint disorders (38%) and obstructive sleep apnoea (23%). 3D cephalometric analysis demonstrated an increased cranial base angle with shortened anterior cranial base and underdevelopment of the maxilla and mandible, with evidence of a reduced pharyngeal airway in 55% of those analysed. Geometric morphometric analysis confirmed that the greatest craniofacial shape variation was among patients with LDS type 2, with distinct clustering of patients with SGS.

CONCLUSIONS

This comprehensive phenotypic approach identifies developmental abnormalities that segregate to mutation variants along the TGF-β signalling pathway, with a particularly severe phenotype associated with TGFBR2 and SKI mutations. Multimodality assessment of craniofacial anomalies objectively reveals the impact of mutations of the TGF-β pathway with perturbations associated with the cranium and cranial base with severe downstream effects on the orbit, maxilla and mandible with the resultant clinical phenotypes.

Connective Tissue Disorders and Cardiovascular Complications: The Indomitable Role of Transforming Growth Factor-β Signaling

Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) represent heritable connective tissue disorders that segregate with a similar pattern of cardiovascular defects (thoracic aortic aneurysm, mitral valve prolapse/regurgitation, and aortic dilatation with regurgitation). This pattern of cardiovascular defects appears to be expressed along a spectrum of severity in many heritable connective tissue disorders and raises suspicion of a relationship between the normal development of connective tissues and the cardiovascular system. With overwhelming evidence of the involvement of aberrant Transforming Growth Factor-beta (TGF-β) signaling in MFS and LDS, this signaling pathway may represent the common link in the relationship between connective tissue disorders and their associated cardiovascular complications. To further explore this hypothetical link, this chapter will review the TGF-β signaling pathway, the heritable connective tissue syndromes related to aberrant TGF-β signaling, and will discuss the pathogenic contribution of TGF-β to these syndromes with a primary focus on the cardiovascular system.

Intraoperative absent bilateral medial recti in syndromic craniosynostosis

Patients with syndromic craniosynostosis are usually associated with the complexity of the malformation complex. We describe here detailed oculo-motility disorder and a remarkable finding of hypoplastic bilateral media recti on imaging and its intraoperative absence in patients with phenotypic features resembling Shprintzen-Goldberg syndrome (SGS). SGS is a rare congenital disorder with craniosynostosis affecting multiple systems including mentation and having a considerable overlap of its phenotypic features with Marfan syndrome. Large A-pattern exotropia found in these patients may be related to the craniofacial features and their bearing on extraocular muscle development and function. In this paper, we aimed to sensitise ophthalmologists and strabismologists concerning the necessity to recognise syndromic associations of patients with craniosynostosis presenting with a large squint, be aware of the intraoperative surprises and consider the challenges in its management.

Multiple Self-Healing Squamous Epithelioma (MSSE): A Digenic Trait Associated with Loss of Function Mutations in TGFBR1 and Variants at a Second Linked Locus on the Long Arm of Chromosome 9

MSSE (Ferguson-Smith disease) is a rare familial condition in which multiple skin tumors resembling squamous carcinomas invade locally and then regress spontaneously after several months, leaving disfiguring scars. We review evidence from haplotype studies in MSSE families with common ancestry that the condition is caused by loss of function mutations in TGFBR1 interacting with permissive variants at a second linked locus on the long arm of chromosome 9. The spectrum of TGFBR1 mutations in MSSE and the allelic disorder Loeys Dietz syndrome (characterized by developmental anomalies and thoracic aortic aneurysms) differ. Reports of patients with both MSSE and Loeys Dietz syndrome are consistent with variants at a second locus determining whether self-healing epitheliomas occur in patients with the loss of function mutations found in most MSSE patients or the missense mutations in the intracellular kinase domain of TGFBR1 that characterize Loeys Dietz syndrome.

Etiology of aortic dissection

We discuss the etiology of aortic dissection (AD) from various points of view. The development of AD requires two pathological conditions: medial degeneration and mechanical wall stress. First, histopathological findings of medial degeneration are hypothesized to be due to a loss of elastic fibers and interconnecting elastic fibers. Damage to the vasa vasorum plays a key role in creating an entry site. The clinical causes of medial degeneration include hypertension, aortic aneurysms, obstructive sleep apnea, and connective tissue disorders. Second, mechanical wall stress is supposedly induced by shear stress caused by blood flow, together with hypertension and aortic root movement. Further investigation is necessary in the search for mechanisms responsible for medial degeneration prior to AD development.

Results of next-generation sequencing gene panel diagnostics including copy-number variation analysis in 810 patients suspected of heritable thoracic aortic disorders

Simultaneous analysis of multiple genes using next-generation sequencing (NGS) technology has become widely available. Copy-number variations (CNVs) in disease-associated genes have emerged as a cause for several hereditary disorders. CNVs are, however, not routinely detected using NGS analysis. The aim of this study was to assess the diagnostic yield and the prevalence of CNVs using our panel of Hereditary Thoracic Aortic Disease (H-TAD)-associated genes. Eight hundred ten patients suspected of H-TAD were analyzed by targeted NGS analysis of 21 H-TAD associated genes. In addition, the eXome hidden Markov model (XHMM; an algorithm to identify CNVs in targeted NGS data) was used to detect CNVs in these genes. A pathogenic or likely pathogenic variant was found in 66 of 810 patients (8.1%). Of these 66 pathogenic or likely pathogenic variants, six (9.1%) were CNVs not detectable by routine NGS analysis. These CNVs were four intragenic (multi-)exon deletions in MYLK, TGFB2, SMAD3, and PRKG1, respectively. In addition, a large duplication including NOTCH1 and a large deletion encompassing SCARF2 were detected. As confirmed by additional analyses, both CNVs indicated larger chromosomal abnormalities, which could explain the phenotype in both patients. Given the clinical relevance of the identification of a genetic cause, CNV analysis using a method such as XHMM should be incorporated into the clinical diagnostic care for H-TAD patients.

Shprintzen-Goldberg syndrome: a rare disorder

Shprintzen-Goldberg Syndrome is an extremely infrequent disorder of connective tissue, characterized by craniosynostosis and marfanoid features, also known as Marfanoid Craniosynostosis syndrome. The syndrome was first introduced by Sugarman and Vogel’ (1981) however, Shprintzen and Goldberg established this as a separate clinical entity in the year 1982. Since then, approximately sixty such cases have been set down in writing in the medical literature. Herein, we present a short review of literature of this rare connective disorder, in order to create awareness about this condition, as the magnitude of this disorder is not measured properly due to the paucity of literature.

MicroRNAs in congenital heart disease

Congenital heart disease (CHD) is a broad term which encompasses a spectrum of pathology, the most common phenotypes include atrial septal defects (ASDs), ventricular septal defects (VSDs), patent ductus arteriosus (PAD) and tetralogy of Fallot (TOF). The impact of CHD is profound and it is estimated to be responsible for over 40% of prenatal deaths. MicroRNAs (miRs) are small, highly conserved, non-coding RNAs which have complex roles in a variety of pathophysiological states. miRs are post-transcriptional negative regulators of gene expression. Individual miRs are known to exert effects in multiple target genes, therefore the altered expression of a single miR could influence an entire gene network resulting in complex pathological states. Recent evidences suggest a role in the dysregulation of miRs in CHD. Mouse knock out models have contributed to our knowledge base revealing specific patterns of miR expression in cardiovascular physiology and pathological states. Specific miRs necessary for embryonic cardiac development have been revealed. Dysregulation of these miRs has been shown to cause structural abnormalities in the heart and vasculature, thus furthering our understanding of the processes which result in CHD. These advances have provided new insight into the signalling pathways responsible for CHD. Furthermore, this new appreciation for miRs in the development of CHD has uncovered their potential for new therapeutic targets where modulated miR activity may reduce the burden of disease. Here, we summarize current knowledge of the cause-effect relationships of miRs in CHD and consider their potential as a therapeutic targets and biomarkers in this clinical setting.

Postoperative mitral leaflet rupture in an infant with Loeys-Dietz syndrome

This report describes an infantile case of Loeys-Dietz syndrome (LDS) with spontaneous mitral leaflet rupture. The patient was diagnosed with a type B interruption of the aortic arch. Bilateral pulmonary artery banding was performed 5 days after birth. On the 53rd day, intra-cardiac repair was performed without valvuloplasty. Although the operation was successful, mitral regurgitation deteriorated at 4 weeks after operation. On the 88th day, a mitral valvuloplasty was performed and a severely ruptured anterior leaflet was observed. Seven days after valvuloplasty, the mitral valve insufficiency again worsened and a fourth operation was performed. Two tears were observed in the anterior and posterior mitral valve leaflets, and a mitral valve replacement was required. Subsequently, the patient was diagnosed with LDS according to gene mutational status. LDS is known to have a poor prognosis with cardiovascular complications, but valve rupture has not been previously reported in other cases.

Critical roles of miRNA-mediated regulation of TGFβ signalling during mouse cardiogenesis

AIMS

MicroRNAs (miRNAs) play critical roles during the development of the cardiovascular system. Blocking miRNA biosynthesis in embryonic hearts through a conditional gene inactivation approach led to differential cardiac defects depending on the Cre drivers used in different studies. The goal of this study is to reveal the cardiogenic pathway that is regulated by the miRNA mechanism at midgestation, a stage that has not been evaluated in previous publications.

METHODS AND RESULTS

We specifically inactivated Dicer1, which is essential for generation of functional mature miRNAs, in the myocardium by crossing cTnt-Cre mice with Dicer1(loxP) mice. cTnt-Cre efficiently inactivates target genes in cardiomyocytes at midgestation. All mutants died between E14.5 and E16.5 with severe myocardial wall defects, including reduced cell proliferation, increased cell death, and spongy myocardial wall. Expression of TGFβ type I receptor (Tgfbr1), which encodes the Type I receptor of TGFβ ligands, was up-regulated in mutant hearts. As expected, TGFβ activity was increased in Dicer1-inactivated hearts. Our further molecular analysis suggested that Tgfbr1 is a direct target of three miRNAs. Reducing TGFβ activities using a pharmacological inhibitor on in vitro cultured hearts, or through an in vivo genetic approach, partially rescued the cardiac defects caused by Dicer1 inactivation.

CONCLUSIONS

We show for the first time that TGFβ signalling is directly regulated by the miRNA mechanism during myocardial wall morphogenesis. Increased TGFβ activity plays a major role in the cardiac defects caused by myocardial deletion of Dicer1. Thus, miRNA-mediated regulation of TGFβ signalling is indispensable for normal cardiogenesis.

Loeys-Dietz syndrome in a Southeast Asian Hospital: a case series

Loeys-Dietz syndrome (LDS) is a heritable connective tissue disease in which the activity of the transforming growth factor (TGF) beta signalling pathway is disrupted. The clinical features of LDS represent a clinical continuum that includes LDS type 1, with cutaneous, vascular, skeletal and craniofacial findings, and LDS type 2, with cutaneous, vascular and skeletal findings. We describe five Asian patients with genetically confirmed LDS with mutations in either the TGFBR1 or TGFBR2 gene. Their clinical features were similar to those reported in Caucasian patients. Two patients have novel mutations in TGFBR2. Transcatheter occlusion of patent ductus arteriosus (PDA) was safe and successful in three patients. Treatment with Losartan for aortic root dilatation was well tolerated in our patients, but the outcome is mixed. Among the three patients with follow-up data, aortic root dilatation has improved in two patients but continues to progress in the third patient despite treatment.

CONCLUSION

We describe two novel mutations in TGFBR2 leading to LDS; PDA is common in our patients and can be safely occluded via transcatheter procedure.

Connective tissue disorders and cardiovascular complications: the indomitable role of transforming growth factor-beta signaling

Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) represent heritable connective tissue disorders that cosegregate with a similar pattern of cardiovascular defects (thoracic aortic aneurysm, mitral valve prolapse/regurgitation, and aortic root dilatation with regurgitation). This pattern of cardiovascular defects appears to be expressed along a spectrum of severity in many heritable connective tissue disorders and raises suspicion of a relationship between the normal development of connective tissues and the cardiovascular system. Given the evidence of increased transforming growth factor-beta (TGF-β) signaling in MFS and LDS, this signaling pathway may represent the common link in this relationship. To further explore this hypothetical link, this chapter will review the TGF-β signaling pathway, heritable connective tissue syndromes related to TGF-β receptor (TGFBR) mutations, and discuss the pathogenic contribution of TGF-β to these syndromes with a primary focus on the cardiovascular system.

Prevalence of dural ectasia in Loeys-Dietz syndrome: comparison with Marfan syndrome and normal controls

BACKGROUND AND PURPOSE

Dural ectasia is well recognized in Marfan syndrome (MFS) as one of the major diagnostic criteria, but the exact prevalence of dural ectasia is still unknown in Loeys-Dietz syndrome (LDS), which is a recently discovered connective tissue disease. In this study, we evaluated the prevalence of dural ectasia in LDS according by using qualitative and quantitative methods and compared our findings with those for with MFS and normal controls.

MATERIAL AND METHODS

We retrospectively studied 10 LDS (6 males, 4 females, mean age 36.3 years) and 20 MFS cases (12 males, 8 females, mean age 37.1 years) and 20 controls (12 males, 8 females, mean age 36.1 years) both qualitatively and quantitatively using axial CT images and sagittal multi-planar reconstruction images of the lumbosacral region. For quantitative examination, we adopted two methods: method-1 (anteroposterior dural diameter of S1> L4) and method-2 (ratio of anteroposterior dural diameter/vertebral body diameter>cutoff values). The prevalence of dural ectasia among groups was compared by using Fisher's exact test and the Tukey-Kramer test.

RESULTS

In LDS patients, the qualitative method showed 40% of dural ectasia, the quantitative method-1 50%, and the method-2 70%. In MFS patients, the corresponding prevalences were 50%, 75%, and 85%, and in controls, 0%, 0%, and 5%. Both LDS and MFS had a significantly wider dura than controls.

CONCLUSIONS

While the prevalence of dural ectasia varied depending on differences in qualitative and quantitative methods, LDS as well as MFS, showed, regardless of method, a higher prevalence of dural ectasia than controls. This finding should help the differentiation of LDS from controls.

Identification of nickel response genes in abnormal early developments of sea urchin by differential display polymerase chain reaction

Bioassays and biomarkers have been previously developed to assess the effects of heavy metal contaminants on the early life stages of the sea urchin. In this study, malformation in the early developmental processes was observed in sea urchin (Strongylocentrotus intermedius) larvae exposed to 10 ppm Ni for over 30 h. The most critical stage at which the triggering of nickel effects takes place is thought to be the blastula stage, which occurs after fertilization in larval development. To investigate the molecular-level responses of sea urchin exposed to heavy metal stress and to explore the differentially expressed genes that are induced or repressed by nickel, differential display polymerase chain reaction (DD-PCR) was used with sea urchin mRNAs. The malformation-related genes expressed in the early life stages of the sea urchin were cloned from larvae exposed to 10 ppm of nickel for 15 h, and accessed via DD-PCR. Sequence analysis results revealed that each of the genes evidenced high homology with EGF2, PCSK9, serine/threonine protein kinase, apolipophorin precursor protein, and MGC80921 protein/transcript variant 2. This result may prove useful in the development of novel biomarkers for the assessment of heavy metal stresses on sea urchin embryos.

Mutations in inhibin and activin genes associated with human disease

Inhibins and activins are members of the transforming growth factor (TGFβ) superfamily, that includes the TGFβs, inhibins and activins, bone morphogenetic proteins (BMPs) and growth and differentiation factors (GDFs). The family members are expressed throughout the human body, and are involved in the regulation of a range of important functions. The precise regulation of the TGFβ pathways is critical, and mutations of individual molecules or even minor alterations of signalling will have a significant affect on function, that may lead to development of disease or predisposition to the development of disease. The inhibins and activins regulate aspects of the male and female reproductive system, therefore, it is not surprising that most of the diseases associated with abnormalities of the inhibin and activin genes are focused on reproductive disorders and reproductive cancers. In this review, I highlight the role of genetic variants in the development of conditions such as premature ovarian failure, pre-eclampsia, and various reproductive cancers. Given the recent advances in human genetic research, such as genome wide association studies and next generation sequencing, it is likely that inhibins and activins will be shown to play more important roles in a range of human genetic diseases in the future.

Prevalence of mitral valve prolapse in residents living at moderately high altitude

OBJECTIVE

Prolapse of mitral valve leaflets is a frequent disorder and the most common cause of severe mitral regurgitation in western countries. However, little is known about the effects of altitude on mitral valve prolapse. We studied the prevalence and echocardiographic characteristics of mitral valve prolapse at moderately high altitude and sea level.

METHODS

A total of 936 consecutive subjects who were admitted to 2 study institutions at Kars, Turkey (1750 m) and Istanbul, Turkey (7 m) were enrolled in this study to determine prevalence of mitral valve prolapse. Demographic and 2-dimensional echocardiographic characteristics of participants were recorded.

RESULTS

Prevalence of mitral valve prolapse was found to be significantly higher in people living at moderate altitude compared with those living at sea level (6.2% vs 2.0%; P = .007). Overall echocardiographic features regarding valve thickness (4.1 ± 0.80 mm vs 3.6 ± 0.66 mm; P = 0.169), maximal valve prolapse (4.6 ± 2.08 mm vs 3.9 ± 0.91 mm; P = .093), and frequency of mitral regurgitation (89% vs 73%; P = .65) were similar between groups, although anterior valve prolapse was seen more frequently at moderate altitude (50% vs 11%; P = .056) and posterior leaflet prolapse was significantly more frequent at sea level (66% vs 10%; P = .002).

CONCLUSIONS

Mitral valve prolapse is more frequently observed at moderately high altitudes. Further studies are needed to determine clinical importance of our findings.

MMP-2 regulates Erk1/2 phosphorylation and aortic dilatation in Marfan syndrome

RATIONALE

Aneurysm and dissection of the ascending thoracic aorta are the main cardiovascular complications of Marfan syndrome (MFS) resulting in premature death. Studies using mouse models of MFS have shown that activation of transforming growth factor-beta (TGF-β) and the concomitant upregulation of matrix metalloproteinases (MMPs) contribute to aneurysm development. Our previous study showed that doxycycline delayed aneurysm rupture in a mouse model of MFS, Fbn1(mgR/mgR). Losartan has been shown to prevent aneurysms in another mouse model of MFS, Fbn1(C1039G/+), through inhibition of the Erk1/2 pathway. However, the role of MMP-2 in MFS and effect of losartan on the lifespan of MFS mice remain unknown.

OBJECTIVE

We investigated the role of MMP-2 in MFS and compared the effects of losartan and doxycycline on aortic dilatation and survival in Fbn1(mgR/mgR) mice.

METHODS AND RESULTS

By life table analysis, we found that losartan and doxycycline improved the survival of Fbn1(mgR/mgR) mice. Gelatin zymography and Western blot data showed that only doxycycline inhibited MMP-2 expression, whereas both drugs decreased Erk1/2 phosphorylation. When combined, only one of nine mice died within the 30-week study; aortic histology and diameter were normalized and the effects on Smad2 phosphorylation was additive. To further explore the role of MMP-2 in MFS, we created MMP-2-deficient Fbn1(mgR/mgR) mice. MMP-2 deletion inhibited activation of TGF-β and phosphorylation of Erk1/2 and Smad2 and prolonged the lifespan of the mice.

CONCLUSIONS

These studies demonstrated that inhibition of MMP-2 by doxycycline delayed the manifestations of MFS, in part, through its ability to decrease active TGF-β and the noncanonical signaling cascade downstream of TGF-β. This study further suggested that targeting TGF-β signaling at different points might be a more effective strategy for inhibiting disease progression.

Clinical features and genetic analysis of Korean patients with Loeys-Dietz syndrome

Loeys-Dietz syndrome (LDS) is an inherited disorder that is characterized by the triad of arterial tortuosity and aneurysms, hypertelorism and a bifid uvula or cleft palate. The disease is caused by heterozygous mutations in the genes encoding transforming growth factor β receptors 1 and 2 (TGFBR1 and TGFBR2, respectively). However, studies of patients with LDS are limited in Korea. From June 2000 to December 2010, 13 patients (10 probands) diagnosed with LDS were enrolled. The multidisciplinary data of the patients were reviewed retrospectively. The frequency of each clinical manifestation in Korean patients with LDS was compared with Western populations as described in the report by Loeys et al. Twelve (92%) of the 13 LDS patients had arterial tortuosity, 9 (69%) patients had hypertelorism and 11 (85%) patients had bifid uvula or cleft palate. Mutations in either TGFBR1 or TGFBR2 were detected in nine probands (90%). Of the mutations, five novel mutations were detected; three in TGFBR2 and two in TGFBR1. Blue sclera and atrial septal defect were not observed in the Korean patients, and the frequency of blue sclera was significantly lower in our Korean population than previously-described Western population (0 vs 40%; P=0.005). Despite the restricted number of patients in our study, we identified five novel mutations in the TGFBR1 and TGFBR2 genes and, except for blue sclera, no differences in phenotype are apparent between Korean patients and Western patients.

Endovascular repair of an internal mammary artery aneurysm in a patient with Loeys-Dietz syndrome

Loeys-Dietz syndrome is a condition that predisposes the development of central and peripheral arterial aneurysms and dissections. The standard approach for treatment of these lesions has been open repair. We present the case of a 34-year-old woman with a previous history of multiple open aortic repairs who presented with a right large internal mammary artery aneurysm. The patient was successfully treated with endovascular coil embolization. This case report demonstrates the feasibility of using endovascular interventions to treat unusual aneurysms in patients with Loeys-Dietz syndrome.

Pregnancy-associated aortic dilatation or dissection in Japanese women with Marfan syndrome

BACKGROUND

Aortic dilatation and dissection are severe complications of pregnancy that may cause maternal death. The purpose of the present study was to investigate risk factors for aortic dilatation or dissection in pregnant Japanese women with Marfan syndrome.

METHODS AND RESULTS

A total of 28 patients with Marfan syndrome were investigated retrospectively during pregnancy and after delivery at 1 institution. These patients were divided into 2 groups: those who experienced aortic dilatation or dissection (group D, n=11) and those who did not (group ND, n = 17). In group D, aortic dilatation or dissection occurred in 7 cases during pregnancy (2 in the 2(nd) trimester, 5 in the 3(rd) trimester) and 4 cases after birth. The 2 cases in the 2nd trimester involved aortic dilatation > 60mm and those patients underwent hemiarch replacement and a David operation, respectively. Delivery by cesarean section (64% vs. 18%, P < 0.05), sinus of Valsalva ≥ 40mm (86% vs. 21%, P < 0.05), aortic size index (size of sinus of Valsalva/body surface area) ≥ 25 mm/m² (7/7, 100% vs. 0/14, 0%, P < 0.0001), and faster growth of the sinus of the Valsalva (median, [interquartile range]: 0.41 mm/month [0.23-0.66 mm/month] vs. 0.05 mm/month [-0.13 to 0.22 mm/month]; P < 0.05) were significantly higher in group D than in group ND.

CONCLUSIONS

A large sinus of Valsalva, increased aortic size index, and rapid growth of the sinus of Valsalva are risk factors for aortic dilatation or dissection in pregnant Japanese women with Marfan syndrome.

Identification of an FBN1 mutation in bovine Marfan syndrome-like disease

Mutations in the gene encoding fibrillin-1 (FBN1), a component of the extracellular microfibril, cause Marfan syndrome (MFS). Frequent observation of cattle with a normal withers height, but lower body weight than age-matched normal cattle, was recently reported among cattle sired by phenotypically normal Bull A, in Japanese Black cattle. These cattle also showed other characteristic features similar to the clinical phenotype of human MFS, such as a long phalanx proximalis, oval face and crystalline lens cloudiness. We first screened a paternal half-sib family comprising 36 affected and 10 normal offspring of Bull A using the BovineSNP50 BeadChip (illumina). Twenty-two microsatellite markers mapped to a significant region on BTA10 were subsequently genotyped on the family. The bovine Marfan syndrome-like disease (MFSL) was mapped onto BTA10. As FBN1 is located in the significant region, FBN1 was sequenced in Bull A, and three affected and one normal cattle. A G>A mutation at the intron64 splicing accepter site (c.8227-1G>A) was detected in 31 of 36 affected animals (84.7%). The c.8227-1G>A polymorphism was not found in 20 normal offspring of Bull A or in 93 normal cattle unrelated to Bull A. The mutation caused a 1-base shift of the intron64 splicing accepter site to the 3' direction, and a 1-base deletion in processed mRNA. This 1-base deletion creates a premature termination codon, and a 125-amino acid shorter Fibrillin-1 protein is produced from the mutant mRNA. We therefore conclude that the c.8227-1G>A mutation is causative for MFSL. Furthermore, it was suggested that Bull A exhibited germline mosaicism for the mutation, and that the frequency of the mutant sperm was 14.9%.

Association of Intracranial Aneurysm and Loeys-Dietz Syndrome: Case Illustration, Management, and Literature Review

BACKGROUND AND IMPORTANCE:

Loeys-Dietz syndrome (LDS) is a newly described connective tissue disease associated with aortic aneurysms. A strong association between LDS and intracranial aneurysms has not yet been documented in the literature. We present the first detailed report of an intracranial aneurysm finding in an LDS patient.

CLINICAL PRESENTATION:

The patient is a 20-year-old female recently diagnosed with LDS and found to harbor 2 incidental intracranial aneurysms on a screening magnetic resonance angiography: a 3-mm right carotid ophthalmic aneurysm and an 8-mm partially fusiform paraclinoid carotid artery aneurysm. A standard left pterional craniotomy was performed. Intraoperative adenosine was used instead of temporary clipping because her vessels were extremely friable. After reconstruction, an intraoperative indocyanine green angiogram was obtained, confirming complete aneurysmal obliteration and internal carotid artery patency.

CONCLUSION:

This is the first detailed report of a clear association between intracranial aneurysms and LDS. An association between LDS and intracranial aneurysms, if substantiated in a larger study, has implications for aneurysm screening in this population. Such an association may shed light on mechanisms of aneurysm formation, growth, and rupture.

Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1

Multiple self-healing squamous epithelioma (MSSE), also known as Ferguson-Smith disease (FSD), is an autosomal-dominant skin cancer condition characterized by multiple squamous-carcinoma-like locally invasive skin tumors that grow rapidly for a few weeks before spontaneously regressing, leaving scars. High-throughput genomic sequencing of a conservative estimate (24.2 Mb) of the disease locus on chromosome 9 using exon array capture identified independent mutations in TGFBR1 in three unrelated families. Subsequent dideoxy sequencing of TGFBR1 identified 11 distinct monoallelic mutations in 18 affected families, firmly establishing TGFBR1 as the causative gene. The nature of the sequence variants, which include mutations in the extracellular ligand-binding domain and a series of truncating mutations in the kinase domain, indicates a clear genotype-phenotype correlation between loss-of-function TGFBR1 mutations and MSSE. This distinguishes MSSE from the Marfan syndrome-related disorders in which missense mutations in TGFBR1 lead to developmental defects with vascular involvement but no reported predisposition to cancer.

Reduction aortoplasty for the ascending aortic aneurysm with aortic valve disease. Does bicuspid valve matter?

BACKGROUND

The outcomes of reduction ascending aortoplasty (RAA) performed with aortic valve surgery were evaluated and the results of RAA in patients with bicuspid aortic valve (BAV) were compared with those in patients with tricuspid valve.

METHODS AND RESULTS

From October 1994 to April 2009, 88 patients underwent RAA. Aortic valve was bicuspid in 45 patients (BAV group) and tricuspid in 43 patients (TAV group). Total circulatory arrest was required in 45 patients. Preoperative ascending aortic diameter was 45.5±4.7mm. Early mortality rate was 1.1%. Ten-year survival rate and freedom from cardiac death were 91.1% and 96.2%, respectively. No differences in clinical outcomes were found between the 2 groups. No aorta-related complications including aortic rupture, dissection and reoperation were observed. Aortic diameter at the last follow-up (61±43 months) was 37.8±4.3mm. The interval between surgery and follow-up CTA was associated with aneurysmal recurrence (P=0.022). Average rate of dilatation was 0.42±0.49mm/year (n=37). A need for total circulatory arrest was associated with an increase of the aortic diameter (P=0.009). BAV was associated with neither aneurysmal recurrence nor increase of aortic diameter.

CONCLUSIONS

RAA in patients with an ascending aortic aneurysm combined with aortic valve disease could be performed with acceptable early and long-term outcomes, even in patients with BAV. Long-term follow-up evaluation might be necessary due to the risk of redilatation especially in patients with an extended aneurysm, which required total circulatory arrest for RAA.

Hereditary disorders of connective tissue: a guide to the emerging differential diagnosis

PURPOSE

To create a practical desk reference for clinicians focused on the differential diagnosis of individuals presenting with features that suggest an inherited disorder of connective tissue.

METHODS

We searched the medical literature for distinct clinical entities that shared clinical features with Marfan syndrome and other classical inherited disorders of connective tissue.

RESULTS

Thirty-six distinct heritable disorders of connective tissue were identified that have overlapping features. These disorders were organized into two matrices according to clinical characteristics and according to causative genes.

CONCLUSIONS

A broad differential diagnosis is emerging for individuals presenting with features suggestive of altered connective tissue. Recent advances in molecular genetics have aided in the delineation of these disorders.

Genetic analysis of young adult patients with aortic disease not fulfilling the diagnostic criteria for Marfan syndrome

BACKGROUND

Although the existence of the young patients with aortic disease not fulfilling the diagnostic criteria for Marfan syndrome (MFS) has been known, the etiology of their disease has not yet been elucidated. The purpose of the present study was to elucidate the genetic and clinical features of the young patients with aortic disease not having MFS.

METHODS AND RESULTS

Eighty young adult patients with aortic disease were examined. They were divided into a definite MFS (n=51) and a non-definite MFS group (n=29) according to the Ghent nosology. Clinical and genetic characteristics were compared between the 2 groups. Among 29 non-definite MFS probands, 1 (3%) FBN1, 2 (7%) TGFBR1, and 3 (10%) TGFBR2 mutations were found, and 4 ACTA2 mutations were found in the 23 probands examined without FBN1, TGFBR1, or TGFBR2 mutations. In total, more than 10 out of 29 (34%) probands in the non-definite MFS group were associated with genetic mutations. Skeletal involvement was less frequent in the non-definite than in the definite MFS group (7% vs 82%, P<0.01).

CONCLUSIONS

In the probands with aortic diseases in young who cannot be diagnosed with MFS, mutations other than FBN1 mutations accounted for at least one-third of all causes of aortic disease.

A new sporadic case of early-onset Loeys-Dietz syndrome due to the recurrent mutation p.R528C in the TGFBR2 gene substantiates interindividual clinical variability

We report on a 2-year-old Polish girl with typical manifestations of Loeys-Dietz syndrome (LDS), a rare genetic condition belonging to the group of Marfan-related disorders. The characteristic LDS symptoms observed in the girl included craniofacial dysmorphism (craniosynostosis, cleft palate, hypertelorism), arachnodactyly, camptodactyly, scoliosis, joint laxity, talipes equinovarus, translucent and hyperelastic skin, and umbilical hernia. Mild dilatation of the ascending aorta and tortuous course of the left internal carotid artery were recognized during her second year of life. Molecular genetic testing revealed a heterozygous missense mutation (c.1582C>T, p.R528C) in the transforming growth factor beta receptor II gene (TGFBR2). This mutation has been previously associated with LDS in 5 unrelated cases, and was never reported in patients with other Marfan-related disorders. Comparison of the phenotypes of our patient and these 5 individuals with c.1582C>T showed that only the hallmark triad of the syndrome - consisting of hypertelorism, aortic root dilatation/aneurysm, and cleft palate or bifid uvula - was present in all 6 cases. Interestingly, none of the 5 individuals who underwent psychological evaluation showed developmental delay. The pattern of all other LDS features showed interindividual variability. Our data support the recently reported observation that symptoms of LDS can develop at a very young age, making early diagnosis and management essential for these patients. This is the first report on a Polish infant with typical LDS symptoms caused by a TGFBR2 mutation.

Loeys-Dietz syndrome type I and type II: clinical findings and novel mutations in two Italian patients

Background

Loeys-Dietz syndrome (LDS) is a rare autosomal dominant disorder showing the involvement of cutaneous, cardiovascular, craniofacial, and skeletal systems. In particular, LDS patients show arterial tortuosity with widespread vascular aneurysm and dissection, and have a high risk of aortic dissection or rupture at an early age and at aortic diameters that ordinarily are not predictive of these events. Recently, LDS has been subdivided in LDS type I (LDSI) and type II (LDSII) on the basis of the presence or the absence of cranio-facial involvement, respectively. Furthermore, LDSII patients display at least two of the major signs of vascular Ehlers-Danlos syndrome. LDS is caused by mutations in the transforming growth factor (TGF) beta-receptor I (TGFBR1) and II (TGFBR2) genes. The aim of this study was the clinical and molecular characterization of two LDS patients.

Methods

The exons and intronic flanking regions of TGFBR1 and TGFBR2 genes were amplified and sequence analysis was performed.

Results

Patient 1 was a boy showing dysmorphic signs, blue sclerae, high-arched palate, bifid uvula; skeletal system involvement, joint hypermobility, velvety and translucent skin, aortic root dilatation, tortuosity and elongation of the carotid arteries. These signs are consistent with an LDSI phenotype. The sequencing analysis disclosed the novel TGFBR1 p.Asp351Gly de novo mutation falling in the kinase domain of the receptor. Patient 2 was an adult woman showing ascending aorta aneurysm, with vascular complications following surgery intervention. Velvety and translucent skin, venous varicosities and wrist dislocation were present. These signs are consistent with an LDSII phenotype. In this patient and in her daughter, TGFBR2 genotyping disclosed in the kinase domain of the protein the novel p.Ile510Ser missense mutation.

Conclusion

We report two novel mutations in the TGFBR1 and TGFBR2 genes in two patients affected with LDS and showing marked phenotypic variability. Due to the difficulties in the clinical approach to a TGFBR-related disease, among patients with vascular involvement, with or without aortic root dilatation and LDS cardinal features, genotyping is mandatory to clarify the diagnosis, and to assess the management, prognosis, and counselling issues.

LRP1 regulates architecture of the vascular wall by controlling PDGFRbeta-dependent phosphatidylinositol 3-kinase activation

BACKGROUND

Low density lipoprotein receptor-related protein 1 (LRP1) protects against atherosclerosis by regulating the activation of platelet-derived growth factor receptor beta (PDGFRbeta) in vascular smooth muscle cells (SMCs). Activated PDGFRbeta undergoes tyrosine phosphorylation and subsequently interacts with various signaling molecules, including phosphatidylinositol 3-kinase (PI3K), which binds to the phosphorylated tyrosine 739/750 residues in mice, and thus regulates actin polymerization and cell movement.

METHODS AND PRINCIPAL FINDINGS

In this study, we found disorganized actin in the form of membrane ruffling and enhanced cell migration in LRP1-deficient (LRP1-/-) SMCs. Marfan syndrome-like phenotypes such as tortuous aortas, disrupted elastic layers and abnormally activated transforming growth factor beta (TGFbeta) signaling are present in smooth muscle-specific LRP1 knockout (smLRP1-/-) mice. To investigate the role of LRP1-regulated PI3K activation by PDGFRbeta in atherogenesis, we generated a strain of smLRP1-/- mice in which tyrosine 739/750 of the PDGFRbeta had been mutated to phenylalanines (PDGFRbeta F2/F2). Spontaneous atherosclerosis was significantly reduced in the absence of hypercholesterolemia in these mice compared to smLRP1-/- animals that express wild type PDGFR. Normal actin organization was restored and spontaneous SMC migration as well as PDGF-BB-induced chemotaxis was dramatically reduced, despite continued overactivation of TGFbeta signaling, as indicated by high levels of nuclear phospho-Smad2.

CONCLUSIONS AND SIGNIFICANCE

Our data suggest that LRP1 regulates actin organization and cell migration by controlling PDGFRbeta-dependent activation of PI3K. TGFbeta activation alone is not sufficient for the expression of the Marfan-like vascular phenotype. Thus, regulation of PI3 Kinase by PDGFRbeta is essential for maintaining vascular integrity, and for the prevention of atherosclerosis as well as Marfan syndrome.

The many faces of aggressive aortic pathology: Loeys-Dietz syndrome

BACKGROUND

Loeys-Dietz syndrome (LDS) is a newly recognised disorder of connective tissue which shares overlapping features with Marfan syndrome (MFS) and the vascular type of Ehlers-Danlos syndrome, including aortic root dilatation and skin abnormalities. It is clinically classified into types 1 and 2. LDS type 1 can be recognised by craniofacial characteristics, e.g. hypertelorism, bifid uvula or cleft palate, whereas these are absent in LDS type 2. It is important to recognise LDS because its vascular pathology is aggressive. We describe nine LDS patients from four families, relate their features to published cases, and discuss important aspects of the diagnosis and management of LDS in order to make clinicians aware of this new syndrome.

RESULTS

Characteristics found in the majority of these LDS patients were aortic root dilatation, cleft palate and/or a bifid/abnormal uvula.

CONCLUSION

Because aortic dissection and rupture in LDS tend to occur at a young age or at aortic root diameters not considered at risk in MFS, and because the vascular pathology can be seen throughout the entire arterial tree, patients should be carefully followed up and aggressive surgical treatment is mandatory. Clinicians must therefore be aware of LDS as a cause of aggressive aortic pathology and that its distinguishing features can sometimes be easily recognised. (Neth Heart J 2008;16:299-304.).

Susceptibility to glaucoma: differential comparison of the astrocyte transcriptome from glaucomatous African American and Caucasian American donors

Comparison of gene expression in normal and glaucomatous eyes from Caucasian American and African American donors reveals differences that might reflect different susceptibility to glaucoma.

Background

Epidemiological and genetic studies indicate that ethnic/genetic background plays an important role in susceptibility to primary open angle glaucoma (POAG). POAG is more prevalent among the African-descent population compared to the Caucasian population. Damage in POAG occurs at the level of the optic nerve head (ONH) and is mediated by astrocytes. Here we investigated differences in gene expression in primary cultures of ONH astrocytes obtained from age-matched normal and glaucomatous donors of Caucasian American (CA) and African American (AA) populations using oligonucleotide microarrays.

Results

Gene expression data were obtained from cultured astrocytes representing 12 normal CA and 12 normal AA eyes, 6 AA eyes with POAG and 8 CA eyes with POAG. Data were normalized and significant differential gene expression levels detected by using empirical Bayesian shrinkage moderated t-statistics. Gene Ontology analysis and networks of interacting proteins were constructed using the BioGRID database. Network maps included regulation of myosin, actin, and protein trafficking. Real-time RT-PCR, western blots, ELISA, and functional assays validated genes in the networks.

Conclusion

Cultured AA and CA glaucomatous astrocytes retain differential expression of genes that promote cell motility and migration, regulate cell adhesion, and are associated with structural tissue changes that collectively contribute to neural degeneration. Key upregulated genes include those encoding myosin light chain kinase (MYLK), transforming growth factor-β receptor 2 (TGFBR2), rho-family GTPase-2 (RAC2), and versican (VCAN). These genes along with other differentially expressed components of integrated networks may reflect functional susceptibility to chronic elevated intraocular pressure that is enhanced in the optic nerve head of African Americans.

Role of transforming growth factor-beta superfamily signaling pathways in human disease

Transforming growth factor beta (TGF-beta) superfamily signaling pathways are ubiquitous and essential regulators of cellular processes including proliferation, differentiation, migration, and survival, as well as physiological processes, including embryonic development, angiogenesis, and wound healing. Alterations in these pathways, including either germ-line or somatic mutations or alterations in the expression of members of these signaling pathways often result in human disease. Appropriate regulation of these pathways is required at all levels, particularly at the ligand level, with either a deficiency or an excess of specific TGF-beta superfamily ligands resulting in human disease. TGF-beta superfamily ligands and members of these TGF-beta superfamily signaling pathways also have emerging roles as diagnostic, prognostic or predictive markers for human disease. Ongoing studies will enable targeting of TGF-beta superfamily signaling pathways for the chemoprevention and treatment of human disease.

A Japanese family of typical Loeys-Dietz syndrome with a TGFBR2 mutation

This report describes a Japanese family with vessel and craniofacial abnormalities. Although the clinical findings of the patient's father fulfilled the diagnostic criteria for Marfan syndrome, arterial tortuosity, aneurysms, hypertelorism and a bifid uvula were noted in both the patient and his father. These findings were compatible with the clinical manifestations that were previously reported in Loeys-Dietz syndrome. A molecular genetic analysis demonstrated a heterozygous missense mutation of the transforming growth factor-beta receptor II gene in both the patient and his father, which thus caused Loeys-Dietz syndrome. This is the first Japanese family case report of typical Loeys-Dietz syndrome.