Sophie Naudion

Marfan Sartan: a randomized, double-blind, placebo-controlled trial.

AIMS To evaluate the benefit of adding Losartan to baseline therapy in patients with Marfan syndrome (MFS). METHODS AND RESULTS A double-blind, randomized, multi-centre, placebo-controlled, add on trial comparing Losartan (50 mg when <50 kg, 100 mg otherwise) vs. placebo in patients with MFS according to Ghent criteria, age >10 years old, and receiving standard therapy. 303 patients, mean age 29.9 years old, were randomized. The two groups were similar at baseline, 86% receiving β-blocker therapy. The median follow-up was 3.5 years. The evolution of aortic diameter at the level of the sinuses of Valsalva was not modified by the adjunction of Losartan, with a mean increase in aortic diameter at the level of the sinuses of Valsalva of 0.44 mm/year (s.e. = 0.07) (-0.043 z/year, s.e. = 0.04) in patients receiving Losartan and 0.51 mm/year (s.e. = 0.06) (-0.01 z/year, s.e. = 0.03) in those receiving placebo (P = 0.36 for the comparison on slopes in millimeter per year and P = 0.69 for the comparison on slopes on z-scores). Patients receiving Losartan had a slight but significant decrease in systolic and diastolic blood pressure throughout the study (5 mmHg). During the study period, aortic surgery was performed in 28 patients (15 Losartan, 13 placebo), death occurred in 3 patients [0 Losartan, 3 placebo, sudden death (1) suicide (1) oesophagus cancer (1)]. CONCLUSION Losartan was able to decrease blood pressure in patients with MFS but not to limit aortic dilatation during a 3-year period in patients >10 years old. β-Blocker therapy alone should therefore remain the standard first line therapy in these patients.

New candidate loci identified by array‐CGH in a cohort of 100 children presenting with syndromic obesity

Syndromic obesity is defined by the association of obesity with one or more feature(s) including developmental delay, dysmorphic traits, and/or congenital malformations. Over 25 syndromic forms of obesity have been identified. However, most cases remain of unknown etiology. The aim of this study was to identify new candidate loci associated with syndromic obesity to find new candidate genes and to better understand molecular mechanisms involved in this pathology. We performed oligonucleotide microarray‐based comparative genomic hybridization in a cohort of 100 children presenting with syndromic obesity of unknown etiology, after exhaustive clinical, biological, and molecular studies. Chromosomal copy number variations were detected in 42% of the children in our cohort, with 23% of patients with potentially pathogenic copy number variants. Our results support that chromosomal rearrangements are frequently associated with syndromic obesity with a variety of contributory genes having relevance to either obesity or developmental delay. A list of inherited or apparently de novo duplications and deletions including their enclosed genes and not previously linked to syndromic obesity was established. Proteins encoded by several of these genes are involved in lipid metabolism (ACOXL, MSMO1, MVD, and PDZK1) linked with nervous system function (BDH1 and LINGO2), neutral lipid storage (PLIN2), energy homeostasis and metabolic processes (CDH13, CNTNAP2, CPPED1, NDUFA4, PTGS2, and SOCS6).

Mutational Spectrum in Holoprosencephaly Shows That FGF is a New Major Signaling Pathway

Holoprosencephaly (HPE) is the most common congenital cerebral malformation in humans, characterized by impaired forebrain cleavage and midline facial anomalies. It presents a high heterogeneity, both in clinics and genetics. We have developed a novel targeted next‐generation sequencing (NGS) assay and screened a cohort of 257 HPE patients. Mutations with high confidence in their deleterious effect were identified in approximately 24% of the cases and were held for diagnosis, whereas variants of uncertain significance were identified in 10% of cases. This study provides a new classification of genes that are involved in HPE. SHH, ZIC2, and SIX3 remain the top genes in term of frequency with GLI2, and are followed by FGF8 and FGFR1. The three minor HPE genes identified by our study are DLL1, DISP1, and SUFU. Here, we demonstrate that fibroblast growth factor signaling must now be considered a major pathway involved in HPE. Interestingly, several cases of double mutations were found and argue for a polygenic inheritance of HPE. Altogether, it supports that the implementation of NGS in HPE diagnosis is required to improve genetic counseling.

International Registry of Patients Carrying TGFBR1 or TGFBR2 Mutations: Results of the MAC (Montalcino Aortic Consortium)

Background—The natural history of aortic diseases in patients with TGFBR1 or TGFBR2 mutations reported by different investigators has varied greatly. In particular, the current recommendations for the timing of surgical repair of the aortic root aneurysms may be overly aggressive. Methods and Results—The Montalcino Aortic Consortium, which includes 15 centers worldwide that specialize in heritable thoracic aortic diseases, was used to gather data on 441 patients from 228 families, with 176 cases harboring a mutation in TGBR1 and 265 in TGFBR2. Patients harboring a TGFBR1 mutation have similar survival rates (80% survival at 60 years), aortic risk (23% aortic dissection and 18% preventive aortic surgery), and prevalence of extra-aortic features (29% hypertelorism, 53% cervical arterial tortuosity, and 27% wide scars) when compared with patients harboring a TGFBR2 mutation. However, TGFBR1 males had a greater aortic risk than females, whereas TGFBR2 males and females had a similar aortic risk. Additionally, aortic root diameter prior to or at the time of type A aortic dissection tended to be smaller in patients carrying a TGFBR2 mutation and was ⩽45 mm in 6 women with TGFBR2 mutations, presenting with marked systemic features and low body surface area. Aortic dissection was observed in 1.6% of pregnancies. Conclusions—Patients with TGFBR1 or TGFBR2 mutations show the same prevalence of systemic features and the same global survival. Preventive aortic surgery at a diameter of 45 mm, lowered toward 40 in females with low body surface area, TGFBR2 mutation, and severe extra-aortic features may be considered.Background— The natural history of aortic diseases in patients with TGFBR1 or TGFBR2 mutations reported by different investigators has varied greatly. In particular, the current recommendations for the timing of surgical repair of the aortic root aneurysms may be overly aggressive. Methods and Results— The Montalcino Aortic Consortium, which includes 15 centers worldwide that specialize in heritable thoracic aortic diseases, was used to gather data on 441 patients from 228 families, with 176 cases harboring a mutation in TGBR1 and 265 in TGFBR2 . Patients harboring a TGFBR1 mutation have similar survival rates (80% survival at 60 years), aortic risk (23% aortic dissection and 18% preventive aortic surgery), and prevalence of extra-aortic features (29% hypertelorism, 53% cervical arterial tortuosity, and 27% wide scars) when compared with patients harboring a TGFBR2 mutation. However, TGFBR1 males had a greater aortic risk than females, whereas TGFBR2 males and females had a similar aortic risk. Additionally, aortic root diameter prior to or at the time of type A aortic dissection tended to be smaller in patients carrying a TGFBR2 mutation and was ≤45 mm in 6 women with TGFBR2 mutations, presenting with marked systemic features and low body surface area. Aortic dissection was observed in 1.6% of pregnancies. Conclusions— Patients with TGFBR1 or TGFBR2 mutations show the same prevalence of systemic features and the same global survival. Preventive aortic surgery at a diameter of 45 mm, lowered toward 40 in females with low body surface area, TGFBR2 mutation, and severe extra-aortic features may be considered.

Expanding the clinical phenotype at the 3q13.31 locus with a new case of microdeletion and first characterization of the reciprocal duplication

Congenital deletions at the 3q13.31 locus have been recently described as a novel microdeletion syndrome characterized by developmental delay, postnatal overgrowth, hypoplastic male genitalia and characteristic facial features. A common critical region of overlapping of 580kb was delineated including two strong candidate genes for developmental delay: DRD3 and ZBTB20. In this report, we describe a new case of 3q13.31 microdeletion identified by array-CGH in a 16year-old girl sharing clinical features commonly observed in the 3q13.31 microdeletion syndrome. This girl had a microdeletion of 7.39Mb spanning the common critical region of overlapping. More interestingly, we report for the first time the existence of a microduplication reciprocal to the microdeletion syndrome. This familial 2.76Mb microduplication identified by array-CGH was carried by two brothers and their father. The phenotype shared by the brothers resembled the phenotype related to the 3q13.31 microdeletion syndrome including especially severe intellectual disability, developmental delay, behavioral abnormalities and obesity. This microduplication involves three strong candidate genes for the developmental delay ZBTB20, LSAMP and GAP43. Further molecular characterization showed that DRD3, another strong candidate gene for developmental delay, was not included in the duplicated region. However, a dosage alteration of this gene cannot be completely excluded as the duplication was inverted at proximity of this gene, as revealed by FISH analysis. Finally, we hypothesized that the phenotype shared by the two brothers could be related to a gene dosage imbalance even if gene expression could not be measured in relevant tissues such as brain or adipocytes.

Otopalatodigital spectrum disorders: refinement of the phenotypic and mutational spectrum

Otopalatodigital spectrum disorders (OPDSD) constitute a group of dominant X-linked osteochondrodysplasias including four syndromes: otopalatodigital syndromes type 1 and type 2 (OPD1 and OPD2), frontometaphyseal dysplasia, and Melnick–Needles syndrome. These syndromes variably associate specific facial and extremities features, hearing loss, cleft palate, skeletal dysplasia and several malformations, and show important clinical overlap over the different entities. FLNA gain-of-function mutations were identified in these conditions. FLNA encodes filamin A, a scaffolding actin-binding protein. Here, we report phenotypic descriptions and molecular results of FLNA analysis in a large series of 27 probands hypothesized to be affected by OPDSD. We identified 11 different missense mutations in 15 unrelated probands (n=15/27, 56%), of which seven were novel, including one of unknown significance. Segregation analyses within families made possible investigating 20 additional relatives carrying a mutation. This series allows refining the phenotypic and mutational spectrum of FLNA mutations causing OPDSD, and providing suggestions to avoid the overdiagnosis of OPD1.

Homozygous and compound heterozygous mutations in the FBN1 gene: unexpected findings in molecular diagnosis of Marfan syndrome

Background Marfan syndrome (MFS) is an autosomal-dominant connective tissue disorder usually associated with heterozygous mutations in the gene encoding fibrillin-1 (FBN1). Homozygous and compound heterozygous cases are rare events and have been associated with a clinical severe presentation. Objectives Report unexpected findings of homozygosity and compound heterozygosity in the course of molecular diagnosis of heterozygous MFS and compare the findings with published cases. Methods and results In the context of molecular diagnosis of heterozygous MFS, systematic sequencing of the FBN1 gene was performed in 2500 probands referred nationwide. 1400 probands carried a heterozygous mutation in this gene. Unexpectedly, among them four homozygous cases (0.29%) and five compound heterozygous cases (0.36%) were identified (total: 0.64%). Interestingly, none of these cases carried two premature termination codon mutations in the FBN1 gene. Clinical features for these carriers and their families were gathered and compared. There was a large spectrum of severity of the disease in probands carrying two mutated FBN1 alleles, but none of them presented extremely severe manifestations of MFS in any system compared with carriers of only one mutated FBN1 allele. This observation is not in line with the severe clinical features reported in the literature for four homozygous and three compound heterozygous probands. Conclusion Homozygotes and compound heterozygotes were unexpectedly identified in the course of molecular diagnosis of MFS. Contrary to previous reports, the presence of two mutated alleles was not associated with severe forms of MFS. Although homozygosity and compound heterozygosity are rarely found in molecular diagnosis, they should not be overlooked, especially among consanguineous families. However, no predictive evaluation of severity should be provided.

Phenotype and genotype analysis of a French cohort of 119 patients with CHARGE syndrome

CHARGE syndrome (CS) is a genetic disorder whose first description included Coloboma, Heart disease, Atresia of choanae, Retarded growth and development, Genital hypoplasia, and Ear anomalies and deafness, most often caused by a genetic mutation in the CHD7 gene. Two features were then added: semicircular canal anomalies and arhinencephaly/olfactory bulb agenesis, with classification of typical, partial, or atypical forms on the basis of major and minor clinical criteria. The detection rate of a pathogenic variant in the CHD7 gene varies from 67% to 90%. To try to have an overview of this heterogenous clinical condition and specify a genotype–phenotype relation, we conducted a national study of phenotype and genotype in 119 patients with CS. Selected clinical diagnostic criteria were from Verloes (2005), updated by Blake & Prasad ( ). Besides obtaining a detailed clinical description, when possible, patients underwent a full ophthalmologic examination, audiometry, temporal bone CT scan, gonadotropin analysis, and olfactory‐bulb MRI. All patients underwent CHD7 sequencing and MLPA analysis. We found a pathogenic CHD7 variant in 83% of typical CS cases and 58% of atypical cases. Pathogenic variants in the CHD7 gene were classified by the expected impact on the protein. In all, 90% of patients had a typical form of CS and 10% an atypical form. The most frequent features were deafness/semicircular canal hypoplasia (94%), pituitary defect/hypogonadism (89%), external ear anomalies (87%), square‐shaped face (81%), and arhinencephaly/anosmia (80%). Coloboma (73%), heart defects (65%), and choanal atresia (43%) were less frequent.

Copy Number Variations Found in Patients with a Corpus Callosum Abnormality and Intellectual Disability

Objective To evaluate the role that chromosomal micro‐rearrangements play in patients with both corpus callosum abnormality and intellectual disability, we analyzed copy number variations (CNVs) in patients with corpus callosum abnormality/intellectual disability Study design We screened 149 patients with corpus callosum abnormality/intellectual disability using Illumina SNP arrays. Results In 20 patients (13%), we have identified at least 1 CNV that likely contributes to corpus callosum abnormality/intellectual disability phenotype. We confirmed that the most common rearrangement in corpus callosum abnormality/intellectual disability is inverted duplication with terminal deletion of the 8p chromosome (3.2%). In addition to the identification of known recurrent CNVs, such as deletions 6qter, 18q21 (including TCF4), 1q43q44, 17p13.3, 14q12, 3q13, 3p26, and 3q26 (including SOX2), our analysis allowed us to refine the 2 known critical regions associated with 8q21.1 deletion and 19p13.1 duplication relevant for corpus callosum abnormality; report a novel 10p12 deletion including ZEB1 recently implicated in corpus callosum abnormality with corneal dystrophy; and) report a novel pathogenic 7q36 duplication encompassing SHH. In addition, 66 variants of unknown significance were identified in 57 patients encompassed candidate genes. Conclusions Our results confirm the relevance of using microarray analysis as first line test in patients with corpus callosum abnormality/intellectual disability.

CHARGE syndrome: a recurrent hotspot of mutations in CHD7 IVS25 analyzed by bioinformatic tools and minigene assays.

CHARGE syndrome is a rare genetic disorder mainly due to de novo and private truncating mutations of CHD7 gene. Here we report an intriguing hot spot of intronic mutations (c.5405-7G > A, c.5405-13G > A, c.5405-17G > A and c.5405-18C > A) located in CHD7 IVS25. Combining computational in silico analysis, experimental branch-point determination and in vitro minigene assays, our study explains this mutation hot spot by a particular genomic context, including the weakness of the IVS25 natural acceptor-site and an unconventional lariat sequence localized outside the common 40 bp upstream the acceptor splice site. For each of the mutations reported here, bioinformatic tools indicated a newly created 3’ splice site, of which the existence was confirmed using pSpliceExpress, an easy-to-use and reliable splicing reporter tool. Our study emphasizes the idea that combining these two complementary approaches could increase the efficiency of routine molecular diagnosis.