Chantal Stheneur

Comparison of Clinical Presentations and Outcomes Between Patients With TGFBR2 and FBN1 Mutations in Marfan Syndrome and Related Disorders

Background— TGFBR2 mutations were recognized recently among patients with a Marfan-like phenotype. The associated clinical and prognostic spectra remain unclear. Methods and Results— Clinical features and outcomes of 71 patients with a TGFBR2 mutation (TGFBR2 group) were compared with 50 age- and sex-matched unaffected family members (control subjects) and 243 patients harboring FBN1 mutations (FBN1 group). Aortic dilatation was present in a similar proportion of patients in both the TGFBR2 and FBN1 groups (78% versus 79%, respectively) but was highly variable. The incidence and average age for thoracic aortic surgery (31% versus 27% and 35±16 versus 39±13 years, respectively) and aortic dissection (14% versus 10% and 38±12 versus 39±9 years) were also similar in the 2 groups. Mitral valve involvement (myxomatous, prolapse, mitral regurgitation) was less frequent in the TGFBR2 than in the FBN1 group (all P<0.05). Aortic dilatation, dissection, or sudden death was the index event leading to genetic diagnosis in 65% of families with TGFBR2 mutations, versus 32% with FBN1 mutations (P=0.002). The rate of death was greater in TGFBR2 families before diagnosis but similar once the disease had been recognized. Most pregnancies were uneventful (without death or aortic dissection) in both TGFBR2 and FBN1 families (38 of 39 versus 213 of 217; P=1). Seven patients (10%) with a TGFBR2 mutation fulfilled international criteria for Marfan syndrome, 3 of whom presented with features specific for Loeys-Dietz syndrome. Conclusions— Clinical outcomes appear similar between treated patients with TGFBR2 mutations and individuals with FBN1 mutations. Prognosis depends on clinical disease expression and treatment rather than simply the presence of a TGFBR2 gene mutation.

Clinical and Molecular Study of 320 Children With Marfan Syndrome and Related Type I Fibrillinopathies in a Series of 1009 Probands With Pathogenic FBN1 Mutations

From a large series of 1009 probands with pathogenic FBN1 mutations, data for 320 patients <18 years of age at the last follow-up evaluation were analyzed (32%). At the time of diagnosis, the median age was 6.5 years. At the last examination, the population was classified as follows: neonatal Marfan syndrome, 14%; severe Marfan syndrome, 19%; classic Marfan syndrome, 32%; probable Marfan syndrome, 35%. Seventy-one percent had ascending aortic dilation, 55% ectopia lentis, and 28% major skeletal system involvement. Even when aortic complications existed in childhood, the rates of aortic surgery and aortic dissection remained low (5% and 1%, respectively). Some diagnostic features (major skeletal system involvement, striae, dural ectasia, and family history) were more frequent in the 10- to <18-year age group, whereas others (ascending aortic dilation and mitral abnormalities) were more frequent in the population with neonatal Marfan syndrome. Only 56% of children could be classified as having Marfan syndrome, according to international criteria, at their last follow-up evaluation when the presence of a FBN1 mutation was not considered as a major feature, with increasing frequency in the older age groups. Eighty-five percent of child probands fulfilled international criteria after molecular studies, which indicates that the discovery of a FBN1 mutation can be a valuable diagnostic aid in uncertain cases. The distributions of mutation types and locations in this pediatric series revealed large proportions of probands carrying mutations located in exons 24 to 32 (33%) and in-frame mutations (75%). Apart from lethal neonatal Marfan syndrome, we confirm that the majority of clinical manifestations of Marfan syndrome increase with age, which emphasizes the poor applicability of the international criteria to this diagnosis in childhood and the need for follow-up monitoring in cases of clinical suspicion of Marfan syndrome.

Nomograms for aortic root diameters in children using two-dimensional echocardiography.

The evaluation of aortic root dilation is of major importance for the diagnosis and follow-up of patients with diverse diseases, including the Marfan syndrome. However, we noted that the available nomograms suggested a lower aortic root dilation rate in adults (75%) than in children (90%), when the opposite would have been expected. To establish new nomograms, we selected a population of 353 normal children. We took transthoracic echocardiographic measurements of the aortic root diameters at the level of the aortic annulus, sinuses of Valsalva, sinotubular junction, and ascending aorta according to the American Society of Echocardiography recommendations. All diameters correlated well with the height, weight, body surface area, and age (r = 0.75 to 0.84, p <0.0001). Covariance analysis adjusting for body surface area showed slightly larger diameters at the level of the sinuses of Valsalva in male children than in female children (+1 mm, p = 0.0002). Equations and derived nomograms were developed, giving the upper limit of normal (allowing simple recognition of aortic dilation) and the Z score (allowing fine quantification of dilation and differentiation of normal growth from pathologic dilation) for all 4 aortic root diameters (ie, aortic annulus, sinuses of Valsalva, sinotubular junction, and proximal ascending aorta) according to body surface area and gender. We applied the nomograms to 282 children with confirmed Marfan syndrome, of whom 65.2% presented with dilation of the sinuses of Valsalva. In conclusion, we propose equations to calculate the upper limit of normal and Z-score for aortic root diameters measured by 2-dimensional echocardiography, which should be useful tools for the diagnosis and follow-up of aortic root aneurysms in children.

Identification of 23 TGFBR2 and 6 TGFBR1 gene mutations and genotype‐phenotype investigations in 457 patients with Marfan syndrome type I and II, Loeys‐Dietz syndrome and related disorders

TGFBR1 and TGFBR2 gene mutations have been associated with Marfan syndrome types 1 and 2, Loeys‐Dietz syndrome and isolated familial thoracic aortic aneurysms or dissection. In order to investigate the molecular and clinical spectrum of TGFBR2 mutations we screened the gene in 457 probands suspected of being affected with Marfan syndrome or related disorders that had been referred to our laboratory for molecular diagnosis. We identified and report 23 mutations and 20 polymorphisms. Subsequently, we screened the TGFBR1 gene in the first 74 patients for whom no defect had been found, and identified 6 novel mutations and 12 polymorphisms. Mutation‐carrying probands displayed at referral a large clinical spectrum ranging from the Loeys‐Dietz syndrome and neonatal Marfan syndrome to isolated aortic aneurysm. Furthermore, a TGFBR1 gene mutation was found in a Shprintzen‐Goldberg syndrome patient. Finally, we observed that the yield of mutation detection within the two genes was very low : 4.8% for classical MFS, 4.6% for incomplete MFS and 1% for TAAD in the TGFBR2 gene; 6.2%, 6.2% and 7% respectively in the TGFBR1 gene; in contrast to LDS, where the yield was exceptionally high (87.5%).

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.

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

Background: The diagnosis of Marfan syndrome (MFS) is usually initially based on clinical criteria according to the number of major and minor systems affected following international nosology. The number of FBN1 mutation carriers, at risk of aortic complications who would not be properly diagnosed based only on clinical grounds, is of growing importance owing to the increased availability of molecular screening. The aim of the study was to identify patients who should be considered for FBN1 mutation screening. Methods: Our international series included 1009 probands with a known FBN1 mutation. Patients were classified as either fulfilling or not fulfilling “clinical” criteria. In patients with unfulfilled “clinical” criteria, we evaluated the percentage of additional patients who became positive for international criteria when the FBN1 mutation was considered. The aortic risk was evaluated and compared in patients fulfilling or not fulfilling the “clinical” international criteria. Results: Diagnosis of MFS was possible on clinical grounds in 79% of the adults, whereas 90% fulfilled the international criteria when including the FBN1 mutation. Corresponding figures for children were 56% and 85%, respectively. Aortic dilatation occurred later in adults with unfulfilled “clinical criteria” when compared to the Marfan syndrome group (44% vs 73% at 40 years, p<0.001), but the lifelong risk for ascending aortic dissection or surgery was not significantly different in both groups. Conclusions: Because of its implications for aortic follow-up, FBN1 molecular analysis is recommended in newly suspected MFS when two systems are involved with at least one major system affected. This is of utmost importance in patients without aortic dilatation and in children.

The new Ghent criteria for Marfan syndrome: What do they change?

Faivre L, Collod‐Beroud G, Adès L, Arbustini E, Child A, Callewaert BL, Loeys B, Binquet C, Gautier E, Mayer K, Arslan‐Kirchner M, Grasso M, Beroud C, Hamroun D, Bonithon‐Kopp C, Plauchu H, Robinson PN, De Backer J, Coucke P, Francke U, Bouchot O, Wolf JE, Stheneur C, Hanna N, Detaint D, De Paepe A, Boileau C, Jondeau G. The new Ghent criteria for Marfan syndrome: what do they change?

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.

Pathogenic FBN1 mutations in 146 adults not meeting clinical diagnostic criteria for Marfan syndrome: further delineation of type 1 fibrillinopathies and focus on patients with an isolated major criterion.

Mutations in the FBN1 gene cause Marfan syndrome (MFS) and have been associated with a wide range of milder overlapping phenotypes. A proportion of patients carrying a FBN1 mutation does not meet diagnostic criteria for MFS, and are diagnosed with “other type I fibrillinopathy.” In order to better describe this entity, we analyzed a subgroup of 146 out of 689 adult propositi with incomplete “clinical” international criteria (Ghent nosology) from a large collaborative international study including 1,009 propositi with a pathogenic FBN1 mutation. We focused on patients with only one major clinical criterion, [including isolated ectopia lentis (EL; 12 patients), isolated ascending aortic dilatation (17 patients), and isolated major skeletal manifestations (1 patient)] or with no major criterion but only minor criteria in 1 or more organ systems (16 patients). At least one component of the Ghent nosology, insufficient alone to make a minor criterion, was found in the majority of patients with isolated ascending aortic dilatation and isolated EL. In patients with isolated EL, missense mutations involving a cysteine were predominant, mutations in exons 24–32 were underrepresented, and no mutations leading to a premature truncation were found. Studies of recurrent mutations and affected family members of propositi with only one major clinical criterion argue for a clinical continuum between such phenotypes and classical MFS. Using strict definitions, we conclude that patients with FBN1 mutation and only one major clinical criterion or with only minor clinical criteria of one or more organ system do exist but represent only 5% of the adult cohort.

Prognosis factors in probands with an FBN1 mutation diagnosed before the age of 1 year.

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder. Diagnostic criteria of neonatal MFS (nMFS), the most severe form, are still debated. The aim of our study was to search for clinical and molecular prognostic factors that could be associated with length of survival. Probands ascertained via the framework of the Universal Marfan database-FBN1, diagnosed before the age of 1 y and presenting with cardiovascular features (aortic root dilatation or valvular insufficiency) were included in this study. Clinical and molecular data were correlated to survival. Among the 60 individuals, 38 had died, 82% died before the age of 1 y, mostly because of congestive heart failure. Three probands reached adulthood. Valvular insufficiencies and diaphragmatic hernia were predictive of shorter life expectancy. Two FBN1 mutations were found outside of the exon 24–32 region (in exons 4 and 21). Mutations in exons 25–26 were overrepresented and were associated with shorter survival (p = 0.03). We report the largest genotyped series of probands with MFS diagnosed before 1 y of life. In this population, factors significantly associated with shorter survival are presence of valvular insufficiencies or diaphragmatic hernia in addition to a mutation in exons 25 or 26.