Contribution of molecular analyses in diagnosing Marfan syndrome and type I fibrillinopathies: an international study of 1009 probands

Preparticipation Cardiac Evaluation from the Pediatric Perspective

Each year millions of children and adolescents undergo sports preparticipation evaluations (PPEs) before participating in organized sports. A primary aim of the PPE is to screen for risk factors associated with sudden cardiac death. This article is designed to summarize the current thoughts on the PPE with a specific slant toward the pediatric and early adolescent evaluation and how these evaluations may differ from those in adults.

Genotype-phenotype correlations of marfan syndrome and related fibrillinopathies: Phenomenon and molecular relevance

Marfan syndrome (MFS, OMIM: 154700) is a heritable multisystemic disease characterized by a wide range of clinical manifestations. The underlying molecular defect is caused by variants in the FBN1. Meanwhile, FBN1 variants are also detected in a spectrum of connective tissue disorders collectively termed as ‘type I fibrillinopathies’. A multitude of FBN1 variants is reported and most of them are unique in each pedigree. Although MFS is being considered a monogenic disorder, it is speculated that the allelic heterogeneity of FBN1 variants contributes to various manifestations, distinct prognoses, and differential responses to the therapies in affected patients. Significant progress in the genotype–phenotype correlations of MFS have emerged in the last 20 years, though, some of the associations were still in debate. This review aims to update the recent advances in the genotype-phenotype correlations of MFS and related fibrillinopathies. The molecular bases and pathological mechanisms are summarized for better support of the observed correlations. Other factors contributing to the phenotype heterogeneity and future research directions were also discussed. Dissecting the genotype-phenotype correlation of FBN1 variants and related disorders will provide valuable information in risk stratification, prognosis, and choice of therapy.

Cysteine Substitution and Calcium-Binding Mutations in FBN1 cbEGF-Like Domains Are Associated With Severe Ocular Involvement in Patients With Congenital Ectopia Lentis

Purpose: To investigate the clinical manifestations of congenital ectopia lentis (CEL) in patients with fibrillin (FBN1) calcium-binding epidermal growth factor (cbEGF)-like mutations.

Design: Retrospective cohort study.

Methods: Consecutive 68 CEL probands with FBN1 cbEGF-like mutations were recruited, mostly comprising Marfan syndrome (MFS) patients. Patients were classified into the cysteine group (n = 43), calcium (Ca²⁺)-binding group (n = 13) or the others (n = 12) according to their genotypes. Ocular biometrics, morbidities and visual performance were compared among different mutation groups. Linear regression was used to evaluate the risk factors for axial length (AL) elongation.

Results: With age-adjustment, cysteine substitution and Ca²⁺-binding mutations positively contributed to AL elongation (standardized coefficient: 0.410 and 0.367, p = 0.008 and 0.017, respectively). In addition, cataract formation was more frequently detected in patients with Ca²⁺-binding mutations (observed n = 3, expected n = 1.0; p = 0.036). Patients with cysteine substitutions had the poorest preoperative visual acuity among the three groups (p = 0.012) and did not recover as well as other patients. More MFS diagnoses were made in patients with cysteine substitutions (observed n = 16, expected n = 12.6), while ectopia lentis syndrome was detected more often in patients with cbEGF-like mutations out of the functional regions (observed n = 6, expected n = 2.5; p = 0.023).

Conclusion: Compared with patients with cbEGF-like mutations out of functional regions, patients with cysteine substitutions or Ca²⁺-binding mutations had longer ALs with age adjustment, poorer ocular involvement, visual performance, and systematic manifestations.

Correlation between FBN1 mutations and ocular features with ectopia lentis in the setting of Marfan syndrome and related fibrillinopathies

Mutations of fibrillin-1 (FBN1) have been associated with Marfan syndrome and pleiotropic connective tissue disorders, collectively termed as "type I fibrillinopathy". However, few genotype-phenotype correlations are known in the ocular system. Patients with congenital ectopia lentis (EL) received panel-based next-generation sequencing, complemented with multiplex ligation-dependent probe amplification. In a total of 125 probands, the ocular phenotypes were compared for different types of FBN1 mutations. Premature termination codons were associated with less severe EL and a thinner central corneal thickness (CCT) than the inframe mutations. The eyes of patients with mutations in the C-terminal region had a higher incidence of posterior staphyloma than those in the middle and N-terminal regions. Mutations in the TGF-β-regulating sequence had larger horizontal corneal diameters (white-to-white [WTW]), higher incidence of posterior staphyloma, but less severe EL than those with mutations in other regions. Mutations in the neonatal region were associated with thinner CCT. Longer axial length (AL) was associated with mutations in the C-terminal region or TGF-β regulating sequence after adjusting for age, EL severity, and corneal curvature radius. FBN1 genotype-phenotype correlations were established for some ocular features, including EL severity, AL, WTW, CCT, and so forth, providing novel perspectives and directions for further mechanistic studies.

Fibrillin-1 gene mutations in a Chinese cohort with congenital ectopia lentis: spectrum and genotype-phenotype analysis

AIMS

To identify the mutation spectrum and genotype-phenotype correlations of fibrillin-1 (FBN1) mutations in a Chinese cohort with congenital ectopia lentis (EL).

METHODS

Patients clinically suspected of congenital zonulopathy were screened using panel-based next-generation sequencing followed by multiplex ligation-dependent probe amplification. All the probands were subjected to thorough ocular examinations. Molecular and clinical data were integrated in pursuit of genotype-phenotype correlation.

RESULTS

A total of 131 probands of FBN1 mutations from unrelated families were recruited. Around 65% of the probands were children younger than 9 years old. Overall, 110 distinct FBN1 mutations were identified, including 39 novel ones. The most at-risk regions were exons 13, 2, 6, 15, 24 and 33 in descending order of mutation frequency. The most prevalent mutation was c.184C>T (seven, 5.34%) in the coding sequence and c.5788+5G>A (three, 2.29%) in introns. Missense mutations were the most frequent type (103, 78.63%); half of which were distributed in the N-terminal regions (53, 51.46%). The majority of missense mutations were detected in one of the calcium-binding epidermal growth factor-like domains (62, 60.19%), and 39 (62.90%) of them were substitutions of conserved cysteine residues. Microspherophakia (MSP) was found in 15 patients (11.45%). Mutations in the middle region (exons 22-42), especially exon 26, had higher risks of combined MSP (OR, 5.51 (95% CI 1.364 to 22.274), p=0.017).

CONCLUSIONS

This study extended the knowledge of the FBN1 mutation spectrum and provided novel insights into its clinical correlation regarding EL and MSP in the Chinese population.

Is there an immunogenomic difference between thoracic and abdominal aortic aneurysms?

BACKGROUND AND AIM

Aortic aneurysms most commonly occur in the infra-renal and proximal thoracic regions. While generally asymptomatic, progressive aneurysmal dilation can become rapidly lethal when dissection or ruptures occurs, highlighting the need for more robust screening. Abdominal aortic aneurysm (AAA) is more prevalent compared to thoracic aortic aneurysm (TAA). The true incidence of TAA is underreported due to the absence of population screening and the silent nature of TAA. To achieve the optimum survival rate in aortic aneurysms, knowledge of natural course, genetic association, and surgical results are needed to be applied with adequate medical treatment and careful selection of patients for operation. The purpose of this paper is to provide a comprehensive review of the literature on natural history, immunology, and genetic differences between thoracic and AAAs.

METHOD

The literature was collected from OVID, SCOPUS, and PubMed.

RESULTS

(1) AAA expands faster than TAA. AAA expands at approximately 0.3-0.45 cm annually, depending on various factors (advancing age, diameter of aorta, smoking etc.). TAA expands up to 0.3 cm annually in a non-bicuspid aortic valve patient. (2) An increase in Matrix metallopeptidase 1, 2, 9, 12, 14 led to degrading extracellular matrix of the aortic vessel wall. This significantly contributed to the pathogenesis in AAA, whereas overactive Transforming growth factor-beta played a major role in the pathogenesis of TAA.

CONCLUSION

In the future, genetic testing may be the gold standard for tackling the geneticheterogeneity of aneurysms, therefore, identifying at-risk individuals developing TAA andAAA earlier.

FBN1 gene mutations in 26 Hungarian patients with suspected Marfan syndrome or related fibrillinopathies

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder mainly affecting the cardiovascular, ocular and musculo-skeletal systems. FBN1 gene mutations lead to MFS and related connective tissue disorders. In this work we described clinical and molecular data of 26 unrelated individuals with suspected MFS who were referred for FBN1 mutation analysis. FBN1 gene sequencing was performed by next generation sequencing and Sanger sequencing methods. We identified 23 causal or potentially causal (including variants of uncertain significance) FBN1 variants, seven of them was novel (˜30%). About 30% of the cases were sporadic. FBN1 mutations were associated with MFS in the majority of the patients, in two cases with severe and early onset manifestation of the syndrome. Missense mutations were detected in 69.6% (16/23), the majority of them were located in one of the cbEGF motifs and ˜70% of them substituted conserved cystein residues. Small deletions/duplications were identified in 13% of the cases (3/23), while splice site variants were detected in 17.4% (4/23). In three unrelated patients a low frequency recurrent silent variant (c.3294C > T (p.Asp1098=) was identified. FBN1 mRNA analysis showed that the mutation does not lead to aberrant splicing, based on available data the mutation was classified as benign.

Ten-year reinvestigation of ocular manifestations in Marfan syndrome

IMPORTANCE

Long-term follow-up of Marfan syndrome (MFS) patients.

BACKGROUND

Investigate changes in ocular features in MFS patients fulfilling the Ghent-2 criteria following a period of 10 years.

DESIGN

Repeated cross-sectional study with two observations.

PARTICIPANTS

Eighty-four MFS patients were investigated in 2003-2004 (baseline). Forty-four of these patients (52%) were examined after 10 years.

METHODS

A comprehensive ocular examination performed at baseline and follow-up.

MAIN OUTCOME MEASURES

Development or progression of ectopia lentis (EL).

RESULTS

At follow-up, mean age was 50.1 ± 11.9 years (range: 30-80 years), 74% were female and 70% of the patients were diagnosed with EL compared to 66% at baseline. Two patients (3 eyes) had developed EL over the decade, representing a 13% risk. Furthermore, one eye had progressed from a subtle tilt of the lens to dislocation. We found no significant change in the axial length (P = 0.96), the corneal curvature (P = 0.64) or the spherical equivalent (P = 0.23). Best corrected visual acuity was improved at follow-up (P = 0.02). There were 7% and 33% risks for development of retinal detachment and cataract between baseline and follow-up, respectively.

CONCLUSIONS AND RELEVANCE

Our study indicates that even though EL typically occurs at an early stage in most MFS patients, there is still a risk of developing EL in adulthood. The risk of developing vision-threatening complications such as retinal detachment and cataract was much higher than in the normal population, but even so, the visual potential of the MFS patients was relatively good.

Association of modifiers and other genetic factors explain Marfan syndrome clinical variability

Marfan syndrome (MFS) is a rare autosomal dominant connective tissue disorder related to variants in the FBN1 gene. Prognosis is related to aortic risk of dissection following aneurysm. MFS clinical variability is notable, for age of onset as well as severity and number of clinical manifestations. To identify genetic modifiers, we combined genome-wide approaches in 1070 clinically well-characterized FBN1 disease-causing variant carriers: (1) an FBN1 eQTL analysis in 80 fibroblasts of FBN1 stop variant carriers, (2) a linkage analysis, (3) a kinship matrix association study in 14 clinically concordant and discordant sib-pairs, (4) a genome-wide association study and (5) a whole exome sequencing in 98 extreme phenotype samples.Three genetic mechanisms of variability were found. A new genotype/phenotype correlation with an excess of loss-of-cysteine variants (P = 0.004) in severely affected subjects. A second pathogenic event in another thoracic aortic aneurysm gene or the COL4A1 gene (known to be involved in cerebral aneurysm) was found in nine individuals. A polygenic model involving at least nine modifier loci (named gMod-M1-9) was observed through cross-mapping of results. Notably, gMod-M2 which co-localizes with PRKG1, in which activating variants have already been described in thoracic aortic aneurysm, and gMod-M3 co-localized with a metalloprotease (proteins of extra-cellular matrix regulation) cluster. Our results represent a major advance in understanding the complex genetic architecture of MFS and provide the first steps toward prediction of clinical evolution.

Interventional repair of a vascular aneurysm in a patient with Marfan syndrome

Marfan syndrome is a heritable connective tissue disorder affecting skeletal, ocular and cardiovascular systems. Cardiovascular manifestations comprise aneurysmal dilatation of aortic root, aortic dissection and rupture; peripheral arterial aneurysms have been reported in femoral, iliac and subclavian arteries with surgical reconstruction as the first-line therapeutic option. We report a Marfan patient with a symptomatic aneurysm of left subclavian artery in the intrathoracic retro-clavicular space; instead of open surgical resection, an endovascular solution was successfully applied by use of a flexible self-expanding stent-graft (W.L Gore^® Viabahn^® Endoprosthesis 9 × 100 mm) to exclude the aneurysm. This case exemplifies a modern option to manage vascular pathology even in patients with Marfan syndrome. Follow-up over 1 year proved very reassuring with complete remodelling and resolution of the aneurysm; long-term follow-up is certainly warranted, considering the potential of recurrence or initial reactive hyperplasia.

Age Differences in Axial Length, Corneal Curvature, and Corneal Astigmatism in Marfan Syndrome with Ectopia Lentis

Purpose

To investigate the differences in axial length, corneal curvature, and corneal astigmatism with age in patients with Marfan syndrome (MFS) and ectopia lentis.

Methods

A retrospective case series study was conducted. MFS patients with ectopia lentis were divided into groups according to age. Axial length, corneal curvature, and corneal astigmatism were measured.

Results

This study included 114 MFS patients (215 eyes) with a mean age of 19.0 ± 13.9 years. Axial length differed significantly across age groups in MFS patients (P < 0.001), whereas corneal curvature did not (P = 0.767). Corneal astigmatism was statistically significant throughout the MFS cohort (P = 0.009), but no significant difference was found in young MFS patients (P = 0.838). With increasing age, the orientation of the corneal astigmatism changed from with-the-rule astigmatism to against-the-rule or oblique astigmatism (P < 0.001). A linear correlation analysis showed weak correlations between age and axial length for both eyes and with corneal astigmatism for the left eye, but there was no correlation between age and corneal curvature.

Conclusions

In MFS, axial length varies with age, corneal curvature remains stable, and corneal astigmatism is higher in young patients and tends to shift toward against-the-rule or oblique astigmatism. Therefore, it is important to consider age when diagnosing MFS with ocular biometric data.

Targeted genetic analysis in a large cohort of familial and sporadic cases of aneurysm or dissection of the thoracic aorta

Purpose

Thoracic aortic aneurysm/aortic dissection (TAAD) is a disorder with highly variable age of onset and phenotype. We sought to determine the prevalence of pathogenic variants in TAAD-associated genes in a mixed cohort of sporadic and familial TAAD patients and identify relevant genotype-phenotype relationships.

Methods

We used a targeted PCR and next generation sequencing-based panel for genetic analysis of 15 TAAD associated genes in 1025 unrelated TAAD cases.

Results

We identified 49 pathogenic or likely pathogenic (P/LP) variants in 47 cases (4.9% of those successfully sequenced). Almost half of the variants were in non-syndromic cases with no known family history of aortic disease. Twenty-five variants were within FBN1 and two patients were found to harbour two P/LP variants. Presence of a related syndrome, younger age at presentation, family history of aortic disease and involvement of the ascending aorta increased the risk of carrying a P/LP variant.

Conclusions

Given the poor prognosis of TAAD that is undiagnosed prior to acute rupture or dissection, genetic analysis of both familial and sporadic cases of TAAD will lead to new diagnoses, more informed management and possibly reduced mortality through earlier, preclinical diagnosis in genetically determined cases and their family members.

Skeletal evolution in Marfan syndrome: growth curves from a French national cohort

BackgroundTo describe the growth patterns of children affected by Marfan syndrome (MFS) compared with those of unaffected children and to create growth charts.MethodsAn observational study of children referred to the French National MFS Reference Centre. A total of 259 children carrying an FBN1 gene mutation and fulfilling Ghent 1 criteria (MFS group) and 474 mutation-negative sibling controls (non-MFS group) were evaluated. Both groups were compared with French-accepted reference nomograms (Reference group).ResultsBoys and girls from the MFS group were significantly taller than those in the non-MFS group and in the reference group at all ages (P<0.0001). But, MFS children's overgrowth reduced with age. At 17 years of age, the mean height (MFS vs. non-MFS) was 191.2±8.4 cm (+2.9 SD) vs. 182.9±8.1 (+1.6 SD) for boys and 178.3±7.6 cm (+2.7 SD) vs. 169.5±6.8 (+1.2 SD) for girls, respectively. By contrast, the mean BMI of children in the MFS group was similar to those in the non-MFS group and inferior to the values of French general population, evolving around -1 SD.ConclusionGrowth patterns differ in patients with an FBN1 mutation. Knowing the growth parameters should allow physicians to better counsel patients and detect the associated diseases. The provided curves could also help to predict the final height.

Long-term follow-up after scleral lens fixation in patients with Marfan syndrome

Background

The dislocation of the crystalline lens is a common finding in patients with Marfan syndrome (MFS). Scleral intraocular lens (IOL) fixation is an accepted treatment method of this complication. To now, no long-term data on scleral IOL fixation in MFS exist.

Methods

We present a retrospective study of 27 eyes of 17 MFS patients that underwent scleral lens fixation at our clinic between 1999 and 2012. These patients are compared to an age- and surgeon-matched group of 31 eyes of 27 patients who underwent the same procedure for reasons other than MFS.

Results

The median age in the MFS group was 35.4 years versus 35.6 years in the non-MFS group. The median follow-up was 4 years for MFS and 3 years for non-MFS. In the MFS group, significantly more IOL-dislocations occurred than compared to the non-MFS group (30% vs. 6.5%, p = 0.02). Retinal detachment occurred in four MFS-eyes compared to three eyes in the non-MFS group. Biometry prediction error was 1.11 diopters (D) for MFS and 1.33 D for non-MFS (p = 0.11). Median BCVA (best-corrected visual acuity, logMAR) was 0.1 in the MFS group versus 0.3 in non-MFS patients.

Conclusion

Scleral lens fixation in MFS patients achieves satisfying visual and refractive outcomes. Our data shows a significantly higher rate of IOL dislocations in patients with MFS. We therefore recommend addressing this complication preoperatively.

Electronic supplementary material

The online version of this article (10.1186/s12886-017-0625-x) contains supplementary material, which is available to authorized users.

A novel FBN1 mutation causes autosomal dominant Marfan syndrome

Marfan syndrome (MFS) is an inherited and systemic disorder. It has been reported that mutations in the fibrillin-1 gene (FBN1) account for ~90% of autosomal dominant cases of MFS. This study was conducted to screen mutations of FBN1 in a Chinese family with autosomal dominant MFS; four individuals including two patients with MFS were recruited. The family members underwent complete physical, cardiovascular and ophthalmologic examinations. Genomic DNA samples were collected from the family along with 383 unrelated healthy subjects. FBN1 coding regions were amplified by polymerase chain reaction and analyzed by direct sequencing. SIFT and PolyPhen-2 were used to predict the possible structural and functional alterations of the protein. A novel heterozygous mutation c.1708 T>G (p.C570G) in exon 14 was identified, which led to a substitution of cysteine by glycine at codon 570 (p.C570G). The mutation was identified as being associated with the MFS phenotype in the affected members of this family. However, the unaffected family members and the 383 normal controls lacked the mutation. Multiple sequence alignment of the human FBN1 protein revealed that this novel mutation occurred within a highly conserved region of the FBN1 protein across different species and may induce structural alterations in this functional domain. The spectrum of MFS-associated mutations in the FBN1 gene has been enriched from this study; this may improve understanding of the molecular pathogenesis and clinical diagnosis of MFS.

Biometry Characteristics in Adults and Children With Marfan Syndrome: From the Marfan Eye Consortium of Chicago

PURPOSE

To report on the biometric findings of adults and children with Marfan syndrome (MFS) recruited from 2 annual National Marfan Foundation conferences (2012 and 2015).

DESIGN

Cross-sectional study.

METHODS

Subjects diagnosed with MFS by Ghent 2 nosology were included for analysis. Subjects were divided into "adults" (≥16 years of age) and "children" (5-15 years of age). Biometric data included values for refractive error, axial length (AL), corneal curvature, anterior chamber depth, lens thickness, and central corneal thickness.

RESULTS

Of the 117 subjects evaluated, 74 (35 adults, 32 children, and 7 children <5 years of age) had a definite diagnosis of MFS and were included in the study. The AL was longer (25.25 ± 0.32 mm vs 24.24 ± 0.33 mm, P = .03) and the lens was thicker (3.94 ± 0.09 mm vs 3.62 ± 0.10 mm, P = .03) in adults. Both groups had flat corneas (average keratometry [K_med] of 41.59 ± 0.35 diopters [D] in adults vs 40.89 ± 0.36 D in children, P = .17). A negative correlation was found between AL and K_med (-0.33, P < .001). The corneas of patients with MFS with ectopia lentis (EL) were significantly flatter and with higher degree of corneal astigmatism compared to patients without EL (K_med of 40.68 ± 0.31 D vs 41.75 ± 0.28 D, P < .01 and corneal astigmatism of 1.68 ± 0.16 D vs 1.13 ± 0.14 D, P = .01).

CONCLUSIONS

Children with established MFS have flat corneas at least to the same degree as adults. Corneas of patients with MFS with EL are flatter and have a higher degree of corneal astigmatism. We strongly suggest that corneal parameters should be measured if MFS is suspected, especially in children that may not yet have developed EL.

Genetic testing in Marfan syndrome

Genetic testing is aiding rapid diagnosis of Marfan syndrome as a basis for management of eye, heart and skeletal disease. The affected patient's mutation can be used as a basis for prenatal or postnatal diagnosis of offspring. Preimplantation genetic diagnosis, the technique of choice, can ensure an unaffected pregnancy.

Does altered aortic flow in marfan syndrome relate to aortic root dilatation?

Purpose

To examine possible hemodynamic alterations in adolescent to adult Marfan syndrome (MFS) patients with aortic root dilatation.

Materials and Methods

Four‐dimensional flow MRI was performed in 20 MFS patients and 12 age‐matched normal subjects with a 3T system. The cross‐sectional areas of 10 planes along the aorta were segmented for calculating the axial and circumferential wall shear stress (WSS_axial, WSS_circ), oscillatory shear index (OSI_axial, OSI_circ), and the nonroundness (NR), presenting the asymmetry of segmental WSS. Pearson's correlation analysis was performed to present the correlations between the quantified indices and the body surface area (BSA), aortic root diameter (ARD), and Z score of the ARD. P < 0.05 indicated statistical significance.

Results

Patients exhibited lower WSS_axial in the aortic root and the WSS_circ in the arch (P < 0.05–0.001). MFS patients exhibited higher OSI_axial and OSI_circ in the sinotubular junction and arch, but lower OSI_circ in the descending aorta (all P < 0.05). The NR values were lower in patients (P < 0.05). The WSS_axial or WSS_circ exhibited moderate to strong correlations with BSA, ARD, or Z score (R² = 0.50–0.72) in MFS patients.

Conclusion

The significant differences in the quantified indices, which were associated with BSA, ARD, or Z score, in MFS were opposite to previous reports for younger MFS patients, indicating that altered flows in MFS patients may depend on the disease progress. The possible time dependency of hemodynamic alterations in MFS patients strongly suggests that longitudinal follow‐up of 4D Flow is needed to comprehend disease progress. J. Magn. Reson. Imaging 2016;44:500–508.

Ocular findings in 87 adults with Ghent-1 verified Marfan syndrome

PURPOSE

To study ocular characteristics in 87 patients with verified Marfan syndrome (MFS) based on the Ghent criteria from 1996 (Ghent-1).

METHODS

The position of the lens was noted by observing the eye in different gaze directions in maximal mydriasis during slit lamp examination. Ectopia lentis (EL) was classified as subluxated (dislocation slightly backwards) or luxated (vertical or horizontal displacement). Corneal curvature, axial length (AL), corneal diameter, central corneal thickness, anterior chamber depth, lens thickness, condition of the iris, intraocular pressure, spherical equivalent and visual acuity were also investigated.

RESULTS

EL was found in 108 eyes (62.1%). Of the 68 phakic eyes with EL, 43 (63.2%) had subluxation. Mean AL was 24.80 ± 2.57 mm, and the AL was above 23.5 mm in 65.3%. Mean keratometry (K) in phakic eyes was 41.79 ± 1.70 diopters (D), and the K value was <41.5D in 46.8%. Iris hypoplasia was found in 3.4%. Myopia above 3D occurred in 38.4% of the phakic eyes. Mean binocular logMAR was 0.10 ± 0.32. Only five patients (5.7%) had a logMAR more than 0.5. These 5 patients had EL, and 4 of them were amblyopic.

CONCLUSION

In this strictly defined MFS group fulfilling the Ghent-1 criteria, the prevalence of EL was 62.1%. In many cases, the dislocation of the lens was subtle. On average, the corneas were flattened and the globe length was increased. Only a few patients were visually impaired. Children with MFS should have a thorough follow up to avoid amblyopia.

Marfan syndrome: An eyesight of syndrome

Marfan syndrome (MFS), a relatively common autosomal dominant hereditary disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular systems, is caused by mutations in the glycoprotein gene fibrillin-1 (FBN1). Aortic root dilation and mitral valve prolapse are the main presentations among the cardiovascular malformations of MFS. The revised Ghent diagnostics nosology of Marfan syndrome is established in accordance with a combination of major and minor clinical manifestations in various organ systems and the family history. The pathogenesis of Marfan syndrome has not been fully elucidated. However, fibrillin-1 gene mutations are believed to exert a dominant negative effect. The treatment includes prophylactic β-blockers and angiotensin II-receptor blockers in order to slow down the dilation of the ascending aorta and prophylactic aortic surgery. Importantly, β-blocker therapy may reduce TGF-β activation, which has been recognized as a contributory factor in MFS. The identification of a mutation allows for early diagnosis, prognosis, genetic counseling, preventive management of carriers and reassurance for unaffected relatives. The importance of knowing in advance the location of the putative family mutation is highlighted by its straightforward application to prenatal and postnatal screening. The present article aims to provide an overview of this rare hereditary disorder.

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The revised Ghent diagnostics nosology is used for MFS detection.

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β-Blockers and angiotensin II-receptor blockers are used in the prophylaxis of MFS.

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MFS mutation identification involve in genetic counseling family members and relatives.

Study of phenotype evolution during childhood in Marfan syndrome to improve clinical recognition

PURPOSE

Because diagnosis of Marfan syndrome is difficult during infancy, we used a large cohort of children to describe the evolution of the Marfan syndrome phenotype with age.

METHODS

Two hundred and fifty-nine children carrying an FBN1 gene mutation and fulfilling Ghent criteria were compared with 474 non-Marfan syndrome children.

RESULTS

Prevalence of skeletal features changed with aging: prevalence of pectus deformity increased from 43% at 0-6 years to 62% at 15-17 years, wrist signs increased from 28 to 67%, and scoliosis increased from 16 to 59%. Hypermobility decreased from 67 to 47% and pes planus decreased from 73 to 65%. Striae increased from 2 to 84%. Prevalence of ectopia lentis remained stable, varying from 66 to 72%, similar to aortic root dilatation (varying from 75 to 80%). Aortic root dilatation remained stable during follow-up in this population receiving β-blocker therapy. When comparing Marfan syndrome children with non-Marfan syndrome children, height appeared to be a simple and discriminant criterion when it was >3.3 SD above the mean. Ectopia lentis and aortic dilatation were both similarly discriminating.

CONCLUSION

Ectopia lentis and aortic dilatation are the best-discriminating features, but height remains a simple discriminating variable for general practitioners when >3.3 SD above the mean. Mean aortic dilatation remains stable in infancy when children receive a β-blocker.

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Cardiovascular magnetic resonance in Marfan syndrome

This review provides an overview of Marfan syndrome with an emphasis on cardiovascular complications and cardiovascular imaging. Both pre- and post-operative imaging is addressed with an explanation of surgical management. All relevant imaging modalities are discussed with a particular focus on cardiovascular MR.

Impact of age and gender on cardiac pathology in children and adolescents with Marfan syndrome

Cardiac pathologies are the major aspect in the treatment strategies for Marfan syndrome (MFS). In this progressive disease, less is known about manifestations and progression of cardiovascular symptoms in children. To define a certain decision regarding therapeutic options, knowledge concerning the onset of cardiovascular findings is essential. From 1998 to 2011, suspected pediatric Marfan patients were subjected to a standardized diagnostic program. Cardiovascular findings were analyzed in terms of age at first clinical manifestation, prevalence and gender differences, morbidity, mortality, and treatment. Marfan syndrome was diagnosed in 82 patients (46 boys; mean age at diagnosis, 9.0 ± 5.7 years). At first presentation, aortic root dilation was found in 56 % of patients, mitral valve prolapse in 31 %, whereas pulmonary artery dilation was detected in 22 % and tricuspid valve prolapse in only 17 % of patients. Aortic (2.5 %) and mitral valve regurgitations (22 %) are significantly correlated with aortic root dilation (p < 0.01) and mitral valve prolapse (p < 0.05) but without relevant progression during childhood. Prophylactic medication was initiated for 42 % of the patients (mean age, 8.0 ± 4.5 years) because of progressive aortic root dilation. Aortic dissection did not appear. Aortic root surgery was needed for 4 % of the patients. Gender-specific differences in cardiovascular findings, progression of disease, or treatment did not appear. Comparable with adults, aortic root dilation is the most frequent cardiovascular finding in children and associated with relevant morbidity, whereas aortic and mitral valve regurgitation are of minor clinical relevance. Manifestation at an early age and slow progression of cardiovascular findings underscore the necessity of repeated echocardiographic examinations for early diagnosis and start of prophylactic treatment.

Systematic molecular and cytogenetic screening of 100 patients with marfanoid syndromes and intellectual disability

The association of marfanoid habitus (MH) and intellectual disability (ID) has been reported in the literature, with overlapping presentations and genetic heterogeneity. A hundred patients (71 males and 29 females) with a MH and ID were recruited. Custom-designed 244K array-CGH (Agilent®; Agilent Technologies Inc., Santa Clara, CA) and MED12, ZDHHC9, UPF3B, FBN1, TGFBR1 and TGFBR2 sequencing analyses were performed. Eighty patients could be classified as isolated MH and ID: 12 chromosomal imbalances, 1 FBN1 mutation and 1 possibly pathogenic MED12 mutation were found (17%). Twenty patients could be classified as ID with other extra-skeletal features of the Marfan syndrome (MFS) spectrum: 4 pathogenic FBN1 mutations and 4 chromosomal imbalances were found (2 patients with both FBN1 mutation and chromosomal rearrangement) (29%). These results suggest either that there are more loci with genes yet to be discovered or that MH can also be a relatively non-specific feature of patients with ID. The search for aortic complications is mandatory even if MH is associated with ID since FBN1 mutations or rearrangements were found in some patients. The excess of males is in favour of the involvement of other X-linked genes. Although it was impossible to make a diagnosis in 80% of patients, these results will improve genetic counselling in families.

New Genetic Insights into Congenital Heart Disease

There has been remarkable progress in understanding the genetic basis of cardiovascular malformations. Chromosome microarray analysis has provided a new tool to understand the genetic basis of syndromic cardiovascular malformations resulting from microdeletion or microduplication of genetic material, allowing the delineation of new syndromes. Improvements in sequencing technology have led to increasingly comprehensive testing for aortopathy, cardiomyopathy, single gene syndromic disorders, and Mendelian-inherited congenital heart disease. Understanding the genetic etiology for these disorders has improved their clinical recognition and management and led to new guidelines for treatment and family-based diagnosis and surveillance. These new discoveries have also expanded our understanding of the contribution of genetic variation, susceptibility alleles, and epigenetics to isolated congenital heart disease. This review summarizes the current understanding of the genetic basis of syndromic and non-syndromic congenital heart disease and highlights new diagnostic and management recommendations.

Candidate gene linkage analysis indicates genetic heterogeneity in Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant disease of the connective tissue that affects the ocular, skeletal and cardiovascular systems, with a wide clinical variability. Although mutations in the FBN1 gene have been recognized as the cause of the disease, more recently other loci have been associated with MFS, indicating the genetic heterogeneity of this disease. We addressed the issue of genetic heterogeneity in MFS by performing linkage analysis of the FBN1 and TGFBR2 genes in 34 families (345 subjects) who met the clinical diagnostic criteria for the disease according to Ghent. Using a total of six microsatellite markers, we found that linkage with the FBN1 gene was observed or not excluded in 70.6% (24/34) of the families, and in 1 family the MFS phenotype segregated with the TGFBR2 gene. Moreover, in 4 families linkage with the FBN1 and TGFBR2 genes was excluded, and no mutations were identified in the coding region of TGFBR1, indicating the existence of other genes involved in MFS. Our results suggest that the genetic heterogeneity of MFS may be greater that previously reported.

The diagnostic value of the facial features of Marfan syndrome

PURPOSE

We examined the prevalence of known facial features of Marfan syndrome (MFS)-dolicocephaly, malar hypoplasia, enophthalmos, retrognathia, and down-slanting palpebral fissures-and the diagnostic utility (sensitivity, specificity, accuracy, predictive values, and likelihood ratios) of using them for screening and diagnosis.

METHODS

Frontal and lateral photographs of 76 subjects with MFS (average age 18.3 years) and of 76 age- and gender-matched controls were obtained, randomized, and compiled into an online survey. Three physicians experienced with MFS rated each photograph for the presence of each feature and indicated whether each photograph triggered a suspicion for MFS. Eight non-expert orthopaedic surgeons reviewed a subset of those photographs and indicated if each triggered a suspicion for MFS. Half of the non-experts then received a brief diagnosis instructional sheet, and all non-experts were retested. The results were compared using Chi-square tests and t-tests with a significance level of P < 0.05.

RESULTS

Using facial features alone, the accuracy of experienced physicians in identifying individuals with MFS was 73%. Facial features had a 54% sensitivity, a 91% specificity, an 86% positive predictive value (PPV), a 67% negative predictive value (NPV), a 6.9% positive likelihood ratio (PLR), and a 50% negative likelihood ratio (NLR) for MFS. There was no significant difference in the diagnostic accuracy between non-experts receiving and not receiving instructions.

CONCLUSIONS

Facial features are more specific than sensitive for MFS. Therefore, the recognition of facial features of MFS can be used as an initial screening tool, but facial features do not have a high sensitivity for MFS.

Cardiovascular manifestations in men and women carrying a FBN1 mutation

AIMS

In patients with Marfan syndrome and other type-1 fibrillinopathies, genetic testing is becoming more easily available, leading to the identification of mutations early in the course of the disease. This study evaluates the cardiovascular (CV) risk associated with the discovery of a fibrillin-1 (FBN1) mutation.

METHODS AND RESULTS

A total of 1,013 probands with pathogenic FBN1 mutations were included, among whom 965 patients [median age: 22 years (11-34), male gender 53%] had data suitable for analysis. The percentage of patients with an ascending aortic (AA) dilatation increased steadily with increasing age and reached 96% (95% CI: 94-97%) by 60 years. The presence of aortic events (dissection or prophylactic surgery) was rare before 20 years and then increased progressively, reaching 74% (95% CI: 67-81%) by 60 years. Compared with women, men were at higher risk for AA dilatation [≤ 30 years: 57% (95% CI: 52-63) vs. 50% (95% CI: 45-55), P = 0.0076] and aortic events [≤ 30 years: 21% (95% CI: 17-26) vs. 11% (95% CI: 8-16), P < 0.0001; adjusted HR: 1.4 (1.1-1.8), P = 0.005]. The prevalence of mitral valve (MV) prolapse [≤ 60 years: 77% (95% CI: 72-82)] and MV regurgitation [≤ 60 years: 61% (95% CI: 53-69)] also increased steadily with age, but surgery limited to the MV remained rare [≤ 60 years: 13% (95% CI: 8-21)]. No difference between genders was observed (for all P> 0.20). From 1985 to 2005 the prevalence of AA dilatation remained stable (P for trend = 0.88), whereas the percentage of patients with AA dissection significantly decreased (P for trend = 0.01).

CONCLUSION

The CV risk remains important in patients with an FBN1 gene mutation and is present throughout life, justifying regular aortic monitoring. Aortic dilatation or dissection should always trigger suspicion of a genetic background leading to thorough examination for extra-aortic features and comprehensive pedigree investigation.

Recent molecular biological progress in Marfan syndrome and Marfan-associated disorders

Marfan syndrome (MFS) is a connective tissue disorder with autosomal dominant inheritance. Advances in medicine and surgery have increased the average lifespan of classically affected patients. Serious visual and/or musculoskeletal impairment often has detrimental effects on day-to-day activities and quality of life. MFS patients suffer from many problems at younger ages and with higher frequencies than the general population because of the degenerative nature of the genetic condition. In classical MFS, changes are caused by mutations in the fibrillin-1 gene (FBN1). Mutations in the fibrillin-2 gene were discovered in individuals with a phenotypically related disorder, congenital contractural arachnodactyly. Some of the clinical manifestations of MFS cannot be explained by mechanical properties alone. Recently, mutations in the genes required for transforming growth factor-beta signaling (TGFBR1 and TGFBR2) have been found in several disorders with varying degrees of overlap with classical MFS, including Loeys-Dietz syndrome and familial thoracic aortic aneurysms and dissections. MFS is a disorder that is variable in its phenotypic expression. Specific information about mutations in the large FBN1 gene will give rise to more information about the phenotype-genotype correlations. Possible molecular mechanisms for the pathogenesis of MFS will be discussed which may assist healthcare professionals to control environmental factors that provoke individual complications in MFS.

Histopathology of an iliac aneurysm in a case of Menkes disease

In Menkes disease, arterial tortuosity is frequent, whereas true aneurysms are rare. Here, we report aneurysmal pathology occurring in an infant with Menkes disease. An iliac aneurysm was diagnosed in a 2-month-old boy and attributed to Menkes syndrome on the basis of plasma copper deficiency. Samples of the aneurysmal wall were taken during surgery for histopathological analysis. As in other forms of aneurysm, the arterial wall was characterized by smooth muscle cell (SMC) disappearance, linked to SMC apoptosis and oxidative stress, areas of mucoid degeneration, and extracellular matrix breakdown, including disappearance of elastic fibers and presence of abnormal collagen.

FBN1 mutations in patients with descending thoracic aortic dissections

Aortic aneurysm and dissection cause significant morbidity and mortality. There are several known single gene disorders that predispose to isolated aortic disease and eventually aneurysm and dissection. FBN1 mutations are associated with multiple clinical phenotypes, including Marfan syndrome (MFS), MASS phenotype, and familial ectopia lentis, but rarely with isolated aortic aneurysm and dissection. In this report, we describe three patients who presented with primary descending thoracic aortic dissection and who were found to have an FBN1 mutation. None of the patients fulfilled clinical criteria for the diagnosis of MFS, and all had few or none of the skeletal features typical of the condition. Two patients had a history of long-term hypertension, and such a history was suspected in the third patient. These observations suggest that some individuals with FBN1 mutations have significant aortic disease involvement of other systems that is typical of FBN1 mutation-related syndromes. Superimposed risk factors, such as hypertension, may weaken the aortic wall and eventually lead to aortic dissection. Given that the cost continues to decrease, we suggest that diagnostic DNA sequencing for FBN1 mutations in patients with thoracic aortic aneurysms and dissection may be a practical clinical step in evaluating such patients and at-risk family members.

Recurrent and founder mutations in the Netherlands: Extensive clinical variability in Marfan syndrome patients with a single novel recurrent fibrillin-1 missense mutation

Background/Methods. Marfan syndrome (MFS) is a heritable connective tissue disorder usually caused by a mutation in the fibrillin 1 (FBN1) gene. Typical characteristics of MFS that have been described include dolichostenomelia, ectopia lentis and aortic root dilatation. However, there is great clinical variability in the expression of the syndrome's manifestations, both between and within families. Here we discuss the clinical variability of MFS by describing a large fourgeneration Dutch family with MFS.Results. Nineteen individuals of one family with a single missense FBN1 mutation (c.7916A>G) were identified. The same mutation was found in one unrelated person. Clinical variability was extensive and not all mutation carriers fulfilled the diagnostic criteria for MFS. Some patients only expressed mild skeletal abnormalities, whereas aortic root dilation was present in eight patients, an acute type A aortic dissection was recorded in two other patients, and a mitral valve prolapse was present in eight patients. In some patients cardiac features were not present on initial screening, but did however develop over time.Conclusion. MFS is a clinically highly variable syndrome, which means a meticulous evaluation of suspected cases is crucial. Mutation carriers should be re-evaluated regularly as cardiovascular symptoms may develop over time. (Neth Heart J 2010;18:85-9.).

Mutation spectrum of the fibrillin-1 (FBN1) gene in Taiwanese patients with Marfan syndrome

The aim of this study was to establish a national database of mutations in the fibrillin-1 (FBN1) gene that cause Marfan syndrome (MFS) in the Taiwanese population. In this study, we screened 294 patients from 157 families for the presence of FBN1 mutations using polymerase chain reaction/ denaturing high performance liquid chromatography (PCR/DHPLC). We identified 56 mutations in 62 of the 157 (40%) families including 49 single-base substitutions (36 missense mutations, seven nonsense mutations, and six splicing sites), one small insertion, four small deletions, one small indel (insertion and deletion), and one exonic deletion (Exon 36). When family history was taken into consideration, the mutation detection rate rose to 91% (29 of 32). We further investigated the phenotypic data and found that one third (47 of 157) of the families fit the Ghent criteria for MFS. Based on that data, the mutation rate was 98% (46/47). That finding implies that family history and the Ghent criteria play a more important role than clinical manifestations in establishing a clinical diagnosis of Marfan syndrome. Among the 56 mutations found in this study, 40 (71%) have not been registered in the Human Gene Mutation Database (HGMD) or in the Universal Mutation Database (UMD). This is the first study of the mutation spectrum of MFS in a cohort of patients in Taiwan. The database is expected to considerably improve genetic counseling for and medical care of MFS families.

Prevalence data on all Ghent features in a cross-sectional study of 87 adults with proven Marfan syndrome

The prevalence of each single feature in the Ghent criteria in patients with Marfan syndrome (MFS) is not known. To elucidate this, a cross-sectional study of 105 adults with presumed MFS was carried out. All patients were examined by the same group of investigators with standardized and complete assessment of all features in the Ghent criteria. Eighty-seven (83%) fulfilled the criteria in 56 different variants. The most prevalent major criterion in Ghent-positive persons was dural ectasia (91%), followed by major genetic criterion (89%) and ectopic lenses (62 %). In 14 persons (16%), the diagnosis was dependent on the dural findings. In all, 79% fulfilled both major dural and major genetic (positive family history and/or FBN1 mutation) criteria, suggesting that most patients with MFS might be identified by investigating these criteria. A history or finding of ascending aortic disease was present in 46 patients (53%). This low prevalence might partly reflect a high number of diagnosed patients encompassing the whole spectrum of the syndrome. The study confirms the need to examine for the complete set of features in the Ghent criteria to identify all patients with MFS. The majority of persons with MFS might be identified by the combined assessment of dura mater and family history, supplemented with DNA analysis in family-negative cases. The low prevalence of ascending aortic disease might indicate better future prospects in an adult population than those traditionally considered.

Identification of the minimal combination of clinical features in probands for efficient mutation detection in the FBN1 gene

Mutations identified in the fibrillin-1 (FBN1) gene have been associated with Marfan syndrome (MFS). Molecular analysis of the gene is classically performed in probands with MFS to offer diagnosis for at-risk relatives and in children highly suspected of MFS. However, FBN1 gene mutations are found in an ill-defined group of diseases termed 'type I fibrillinopathies', which are associated with an increased risk of aortic dilatation and dissection. Thus, there is growing awareness of the need to identify these non-MFS probands, for which FBN1 gene screening should be performed. To answer this need we compiled the molecular data obtained from the screening of the FBN1 gene in 586 probands, which had been addressed to our laboratory for molecular diagnosis. In this group, the efficacy of FBN1 gene screening was high in classical MFS probands (72.5%,), low (58%) in those referred for incomplete MFS and only slight (14.3%) for patients referred as possible MFS. Using recursive partitioning, we found that the best predictor of the identification of a mutation in the FBN1 gene was the presence of features in at least three organ systems, combining one major, and various minor criteria. We also show that our original recommendation of two systems involved with at least one with major criterion represents the minimal criteria because in probands not meeting these criteria, the yield of mutation identification drastically falls. This recommendation should help clinicians and biologists in identifying probands with a high probability of carrying a FBN1 gene mutation, and thus optimize biological resources.