Genetic diagnosis of the Ehlers-Danlos syndromes

The Ehlers-Danlos syndromes (EDS) represent a group of genetically diverse disorders characterized by the variable combination of joint hypermobility, hyperextensibility of the skin, and connective tissue fragility affecting the skin and other organs. Based on clinical features, 13 different types of EDS have been delineated, 12 of which represent monogenic conditions caused by pathogenic variants in 21 confirmed genes. Pathogenesis is related to disturbances of collagen formation and/or stability. No monogenic cause has been identified for hypermobile EDS (hEDS), a more common EDS type, which is unlikely to represent a single gene disorder in the majority of affected individuals and at present cannot be diagnosed by genetic investigations. Here we summarize the clinical features and the molecular bases of the monogenic EDS types, highlight diagnostic challenges, and provide guidance for the molecular work-up of affected individuals. In general, genetic tests are indicated if clinical features suggest a monogenic EDS type but are usually unrewarding for other cases of hypermobility.</p

Spontaneous Coronary Artery Dissection as Presenting Feature of Vascular Ehlers-Danlos Syndrome

A spontaneous coronary artery dissection as the sole presenting feature of vascular Ehlers-Danlos syndrome is an uncommon finding. We present a 33-year-old woman with sudden onset chest pain caused by a spontaneous coronary artery dissection. Genetic testing revealed vascular Ehlers-Danlos syndrome as the underlying cause. Specifically, we show the value of genetic testing, which in some patients may be the only way of establishing a diagnosis

Clinical diagnosis of the monogenic Ehlers-Danlos syndromes

Monogenic Ehlers-Danlos syndromes (EDS) are a group of inherited connective tissue conditions that are clinically characterised by joint hypermobility, skin hyperextensibility and/or fragility, and generalised tissue fragility. Gene panel testing with massively parallel sequencing is currently gold standard to confirm diagnoses of the monogenic EDS types. We aim to report on the (combination of) clinical features of the monogenic EDS types through text and photographs, to aid clinical diagnosis as despite the significant progress in genetic testing possibilities, a thorough clinical assessment which includes medical history, family history and physical examination remains important in the diagnostic process. In addition, in those cases where no molecular diagnosis is possible, a clinical diagnosis can still guide management and surveillance.</p

Tenascin-X Deficiency Causing Classical-Like Ehlers-Danlos Syndrome Type 1 in Humans is a Significant Risk Factor of Gastrointestinal and Tracheal Ruptures

INTRODUCTION:Classical-like Ehlers-Danlos syndrome type 1 (clEDS1) is a very rare form of Ehlers-Danlos syndrome caused by tenascin-X deficiency, with only 56 individuals reported in medical literature. Tenascin-X is an extracellular matrix protein needed for collagen stability. Previous publications propose that individuals with clEDS1 might be at risk of gastrointestinal (GI) tract perforations and/or tracheal ruptures. The aim of this study was to characterize complications resulting from perforations of the GI tract and/or tracheal rupture in an international case series of individuals with clEDS1 due to disease-related tissue fragility.METHODS:This case series includes individuals with confirmed clEDS1 and GI perforations and/or tracheal ruptures from participating centers. Researchers who previously reported such individuals were contacted for additional information. A retrospective assessment of clinical features was performed.RESULTS:Fifteen individuals were included. Ten had spontaneous GI perforations, 7 of whom had multiple GI perforations. Almost all had severe diverticulosis. Three individuals experienced iatrogenic tracheal ruptures.DISCUSSION:Severe GI complications, such as perforation, and tracheal rupture were observed in a substantial number of individuals with clEDS1. As these features seem significantly more common in clEDS1 than in the average population, we advise vigilance during intubation and GI endoscopic interventions of individuals with clEDS1. Routine referrals to clinical geneticists are recommended for patients with symptoms indicative of clEDS1, especially with unexplained GI perforations and connective tissue symptoms. Our findings offer valuable insights for the clinical management of clEDS1 and underscore the importance of specialized care, providing a foundation for improved clinical guidelines and preventive strategies.</p

Biallelic and monoallelic variants in EFEMP1 can cause a severe and distinct subtype of heritable connective tissue disorder

Variants in EFEMP1, encoding Fibulin-3, were previously reported as a rare cause of heritable connective tissue disorder (HCTD) with recurrent hernias and joint hypermobility. We report three new cases with biallelic or monoallelic EFEMP1 variants and severe hernia phenotypes. Two male siblings of 10 and 13 years old presented with marfanoid habitus, recurrent inguinal and umbilical hernias, generalized joint hypermobility, and scoliosis. Parents and halfsiblings reported joint hypermobility and umbilical hernias. The eldest boy died at age 16 from incarcerated gastrointestinal herniation complicated by gastric and bowel necrosis with perforation. Autopsy revealed widespread intestinal diverticula. Immunohistochemistry of skin and fascia tissue did not reveal any abnormalities, including normal staining of elastic fibers. Both siblings harbored compound heterozygous likely pathogenic EFEMP1 variants (c.1320 + 2T > A, p.? and c.698G > A, p.Gly233Asp). An unrelated 58-year-old male had marfanoid features, high myopia, recurrent diaphragmatic and inguinal hernias, and chronic gastrointestinal dilatation with severe malabsorption. Both his dizygotic twin-brother and mother had recurrent hernias and high myopia. This man died at 59 years of age, and autopsy showed extensive diaphragmatic herniation, bowel diverticula, and pulmonary emphysema. A heterozygous EFEMP1 splice-variant (c.81 + 1G > A, p.?) was identified, causing exon skipping leading to a start-loss. Targeted genome reanalysis nor RNA-sequencing revealed a second variant at the other allele. The reported individuals expand the clinical and pathological phenotypes of EFEMP1-related disease, a distinct entity within the spectrum of HCTD. The severe and recurrent hernias, gastrointestinal dilatation, and diverticulosis result in an increased risk for life-threatening complications, demanding early recognition and close monitoring. MTG

Untargeted metabolomics-based screening method for inborn errors of metabolism using semi-automatic sample preparation with an UHPLC-orbitrap-MS platform

Routine diagnostic screening of inborn errors of metabolism (IEM) is currently performed by different targeted analyses of known biomarkers. This approach is time-consuming, targets a limited number of biomarkers and will not identify new biomarkers. Untargeted metabolomics generates a global metabolic phenotype and has the potential to overcome these issues. We describe a novel, single platform, untargeted metabolomics method for screening IEM, combining semi-automatic sample preparation with pentafluorophenylpropyl phase (PFPP)-based UHPLC-Orbitrap-MS. We evaluated analytical performance and diagnostic capability of the method by analysing plasma samples of 260 controls and 53 patients with 33 distinct IEM. Analytical reproducibility was excellent, with peak area variation coefficients below 20% for the majority of the metabolites. We illustrate that PFPP-based chromatography enhances identification of isomeric compounds. Ranked z-score plots of metabolites annotated in IEM samples were reviewed by two laboratory specialists experienced in biochemical genetics, resulting in the correct diagnosis in 90% of cases. Thus, our untargeted metabolomics platform is robust and differentiates metabolite patterns of different IEMs from those of controls. We envision that the current approach to diagnose IEM, using numerous tests, will eventually be replaced by untargeted metabolomics methods, which also have the potential to discover novel biomarkers and assist in interpretation of genetic data

Using out-of-batch reference populations to improve untargeted metabolomics for screening inborn errors of metabolism

Untargeted metabolomics is an emerging technology in the laboratory diagnosis of inborn errors of metabolism (IEM). Analysis of a large number of reference samples is crucial for correcting variations in metabolite concentrations that result from factors, such as diet, age, and gender in order to judge whether metabolite levels are abnormal. However, a large number of reference samples requires the use of out-of-batch samples, which is hampered by the semi-quantitati

Comprehensive study of 28 individuals with SIN3A-related disorder underscoring the associated mild cognitive and distinctive facial phenotype

Witteveen-Kolk syndrome (OMIM 613406) is a recently defined neurodevelopmental syndrome caused by heterozygous loss-of-function variants in SIN3A. We define the clinical and neurodevelopmental phenotypes related to SIN3A-haploinsufficiency in 28 unreported patients. Patients with SIN3A variants adversely affecting protein function have mild intellectual disability, growth and feeding difficulties. Involvement of a multidisciplinary team including a geneticist, pediatrician and neurologist should be considered in managing these patients. Patients described here were identified through a combination of clinical evaluation and gene matching strategies (GeneMatcher and Decipher). All patients consented to participate in this study. Mean age of this cohort was 8.2 years (17 males, 11 females). Out of 16 patients ≥ eight years old assessed, eight (50%) had mild intellectual disability (ID), four had moderate ID (22%), and one had severe ID (6%). Four (25%) did not have any cognitive impairment. Other neurological symptoms such as seizures (4/28) and hypotonia (12/28) were common. Behaviour problems were reported in a minority. In patients ≥2 years, three were diagnosed with Autism Spectrum Disorder (ASD) and four with Attention Deficit Hyperactivity Disorder (ADHD). We report 27 novel variants and one previously reported variant. 24 were truncating variants; three were missense variants and one large in-frame gain including exons 10-12.