COL1-related overlap disorder: A novel connective tissue disorder incorporating the osteogenesis imperfecta/Ehlers-Danlos syndrome overlap

Pathogenic mechanisms in genetically defined Ehlers-Danlos syndromes

The Ehlers-Danlos syndromes (EDS) are a group of rare heritable connective tissue disorders, common hallmarks of which are skin hyperextensibility, joint hypermobility, and generalized connective tissue fragility. Currently, 13 EDS types are recognized, caused by defects in 20 genes which consequently alter biosynthesis, organization, and/or supramolecular assembly of collagen fibrils in the extracellular matrix (ECM). Molecular analyses on patient samples (mostly dermal fibroblast cultures), combined with studies on animal models, have highlighted that part of EDS pathogenesis can be attributed to impaired cellular dynamics. Although our understanding of the full extent of (extra)cellular consequences is still limited, this narrative review aims to provide a comprehensive overview of our current knowledge on the extracellular, pericellular, and intracellular alterations implicated in EDS pathogenesis.

Whole exome sequencing and proteomics-based investigation of the pathogenesis of coronary artery disease with diffuse long lesion

OBJECTIVES

The long-term prognosis of patients with coronary artery disease (CAD) with diffuse long lesion underwent coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI) remains worse. Here, we aimed to identify distinctive genes involved and offer novel insights into the pathogenesis of diffuse long lesion.

MATERIALS AND METHODS

Whole exome sequencing was performed on peripheral blood samples from 20 CAD patients with diffuse long lesion (CAD-DLL) and from 10 controls with focal lesion (CAD-FL) through a uniform pipeline. Proteomics analysis was conducted on the serum samples from 10 CAD-DLL patients and from 10 controls with CAD-FL by mass spectrometry. Bioinformatics analysis was performed to elucidate the involved genes, including functional annotation and protein-protein interaction analysis.

RESULTS

A total of 742 shared variant genes were found in CAD-DLL patients but not in controls. Of these, 46 genes were identified as high-frequency variant genes (≥ 4/20) distinctive genes. According to the consensus variant site, 148 shared variant sites were found in the CAD-DLL group. The lysosome and cellular senescence-related pathway may be the most significant pathway in diffuse long lesion. Following the DNA-protein combined analysis, eight genes were screened whose expression levels were altered at both DNA and protein levels. Among these genes, the MAN2A2 gene, the only one that was highly expressed at the protein level, was associated with metabolic and immune-inflammatory dysregulation.

CONCLUSIONS

Compared to individuals with CAD-FL, patients with CAD-DLL show additional variants. These findings contribute to the understanding of the mechanism of CAD-DLL and provide potential targets for the diagnosis and treatment of CAD-DLL.

Echocardiographic abnormalities and joint hypermobility in Chinese patients with Osteogenesis imperfecta

BACKGROUND

Very little is known about the characteristics of echocardiographic abnormalities and joint hypermobility in Chinese patients with osteogenesis imperfecta (OI). The aim of our study was to investigate the characteristics, prevalence and correlation of echocardiographic abnormalities and joint hypermobility in Chinese patients with OI.

METHODS

A cross-sectional comparative study was conducted in pediatric and adult OI patients who were matched in age and sex with healthy controls. Transthoracic echocardiography was performed in all patients and controls, and parameters were indexed for body surface area (BSA). The Beighton score was used to evaluate the degree of joint hypermobility.

RESULTS

A total of 48 patients with OI (25 juveniles and 23 adults) and 129 age- and sex-matched healthy controls (79 juveniles and 50 adults) were studied. Four genes (COL1A1, COL1A2, IFITM5, and WNT1) and 39 different mutation loci were identified in our study. Mild valvular regurgitation was the most common cardiac abnormality: mild mitral and tricuspid regurgitation was found in 12% and 36% of pediatric OI patients, respectively; among 23 OI adults, 13% and 17% of patients had mild mitral and tricuspid regurgitation, respectively, and 4% had mild aortic regurgitation. In multiple regression analysis, OI was the key predictor of left atrium diameter (LAD) (β=-3.670, P < 0.001) and fractional shortening (FS) (β = 3.005, P = 0.037) in juveniles, whereas for adults, OI was a significant predictor of LAD (β=-3.621, P < 0.001) and left ventricular mass (LVM) (β = 58.928, P < 0.001). The percentages of generalized joint hypermobility in OI juveniles and adults were 56% and 20%, respectively. Additionally, only in the OI juvenile group did the results of the Mann‒Whitney U test show that the degree of joint hypermobility was significantly different between the echocardiographic normal and abnormal groups (P = 0.004).

CONCLUSIONS

Mild valvular regurgitation was the most common cardiac abnormality in both OI juveniles and adults. Compared with OI adults, OI juveniles had more prevalent and wider joint hypermobility. Echocardiographic abnormalities may imply that the impairment of type I collagen is more serious in OI. Baseline echocardiography should be performed in OI patients as early as possible.

Placing joint hypermobility in context: traits, disorders and syndromes

BACKGROUND

Joint hypermobility (JHM) is a common physical trait. It may occur alone or in combination with musculoskeletal (MSK) pain, outside or within more complex phenotypes. Hypermobility spectrum disorders (HSD) are diagnosed in individuals with JHM and related MSK pain, when an alternative diagnosis cannot be identified. Conversely, the Ehlers-Danlos syndrome (EDS) encompasses a group of rare hereditary connective tissue disorders featuring JHM along with other pleiotropic manifestations. The 2017 EDS Classification identifies 13 different subtypes. Hypermobile EDS (HEDS) is the only EDS variant still lacking a confirmatory test.

SOURCES OF DATA

Literature was reviewed searching for the most relevant papers related to key arguments. Particular attention was focused on papers published after the 2017 Classification.

AREAS OF AGREEMENT

Definition, epidemiology, assessment tools and patterns of JHM are presented. The morbid nature of the 2017 EDS Classification and of the 'spectrum' is also illustrated.

AREAS OF CONTROVERSY

We discuss current limitations and disagreements concerning the 'spectrum', HSD and HEDS.

GROWING POINTS

In the clinical context, elucidation of the pathophysiology of pain related to JHM should develop in parallel with the analysis of pleiotropic manifestations of syndromes with JHM.

AREAS TIMELY FOR DEVELOPING RESEARCH

Future challenges concerning classification, nosology, diagnosis and management of JHM, EDS and related disorders are discussed.

Contribution of common and rare variants to Asian neovascular age-related macular degeneration subtypes

Neovascular age-related macular degeneration (nAMD), along with its clinical subtype known as polypoidal choroidal vasculopathy (PCV), are among the leading causes of vision loss in elderly Asians. In a genome-wide association study (GWAS) comprising 3,128 nAMD (1,555 PCV and 1,573 typical nAMD), and 5,493 controls of East Asian ancestry, we identify twelve loci, of which four are novel ([Formula: see text]). Substantial genetic sharing between PCV and typical nAMD is noted (rg = 0.666), whereas collagen extracellular matrix and fibrosis-related pathways are more pronounced for PCV. Whole-exome sequencing in 259 PCV patients revealed functional rare variants burden in collagen type I alpha 1 chain gene (COL1A1; [Formula: see text]) and potential enrichment of functional rare mutations at AMD-associated loci. At the GATA binding protein 5 (GATA5) locus, the most significant GWAS novel loci, the expressions of genes including laminin subunit alpha 5 (Lama5), mitochondrial ribosome associated GTPase 2 (Mtg2), and collagen type IX alpha 3 chain (Col9A3), are significantly induced during retinal angiogenesis and subretinal fibrosis in murine models. Furthermore, retinoic acid increased the expression of LAMA5 and MTG2 in vitro. Taken together, our data provide insights into the genetic basis of AMD pathogenesis in the Asian population.

Prevalence of Monogenic Bone Disorders in a Dutch Cohort of Atypical Femur Fracture Patients

Atypical femur fractures (AFFs), considered rare associations of bisphosphonates, have also been reported in patients with monogenic bone disorders without bisphosphonate use. The exact association between AFFs and monogenic bone disorders remains unknown. Our aim was to determine the prevalence of monogenic bone disorders in a Dutch AFF cohort. AFF patients were recruited from two specialist bone centers in the Netherlands. Medical records of the AFF patients were reviewed for clinical features of monogenic bone disorders. Genetic variants identified by whole-exome sequencing in 37 candidate genes involved in monogenic bone disorders were classified based on the American College of Medical Genetics and Genomics (ACMG) classification guidelines. Copy number variations overlapping the candidate genes were also evaluated using DNA array genotyping data. The cohort comprises 60 AFF patients (including a pair of siblings), with 95% having received bisphosphonates. Fifteen AFF patients (25%) had clinical features of monogenic bone disorders. Eight of them (54%), including the pair of siblings, had a (likely) pathogenic variant in either PLS3, COL1A2, LRP5, or ALPL. One patient carried a likely pathogenic variant in TCIRG1 among patients not suspected of monogenic bone disorders (2%). In total, nine patients in this AFF cohort (15%) had a (likely) pathogenic variant. In one patient, we identified a 12.7 Mb deletion in chromosome 6, encompassing TENT5A. The findings indicate a strong relationship between AFFs and monogenic bone disorders, particularly osteogenesis imperfecta and hypophosphatasia, but mainly in individuals with symptoms of these disorders. The high yield of (likely) pathogenic variants in AFF patients with a clinical suspicion of these disorders stresses the importance of careful clinical evaluation of AFF patients. Although the relevance of bisphosphonate use in this relationship is currently unclear, clinicians should consider these findings in medical management of these patients. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Specifications and validation of the ACMG/AMP criteria for clinical interpretation of sequence variants in collagen genes associated with joint hypermobility

Deleterious variants in collagen genes are the most common cause of hereditary connective tissue disorders (HCTD). Adaptations of the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) criteria are still lacking. A multidisciplinary team was set up for developing specifications of the ACMG/AMP criteria for COL1A1, COL1A2, COL2A1, COL3A1, COL5A1, COL5A2, COL11A1, COL11A2 and COL12A1, associated with various forms of HCTD featuring joint hypermobility, which is becoming one of the most common reasons of referral for molecular testing in this field. Such specifications were validated against 209 variants, and resulted effective for classifying as pathogenic and likely pathogenic null alleles without downgrading of the PVS1 level of strength and recurrent Glycine substitutions. Adaptations of selected criteria reduced uncertainties on private Glycine substitutions, intronic variants predicted to affect the splicing, and null alleles with a downgraded PVS1 level of strength. Segregation and multigene panel sequencing data mitigated uncertainties on non-Glycine substitutions by the attribution of one or more benignity criteria. These specifications may improve the clinical utility of molecular testing in HCTD by reducing the number of variants with neutral/conflicting interpretations. Close interactions between laboratory and clinicians are crucial to estimate the a priori utility of molecular test and to improve medical reports.

Degradation of collagen I by activated C1s in periodontal Ehlers-Danlos Syndrome

Periodontal Ehlers-Danlos syndrome (pEDS) is an autosomal dominant disorder characterized by early-onset periodontitis leading to premature loss of teeth, lack of attached gingiva and thin and fragile gums leading to gingival recession. Connective tissue abnormalities of pEDS typically include easy bruising, pretibial plaques, distal joint hypermobility, hoarse voice, and less commonly manifestations such as organ or vessel rupture. pEDS is caused by heterozygous missense mutations in C1R and C1S genes of the classical complement C1 complex. Previously we showed that pEDS pathogenic variants trigger intracellular activation of C1r and/or C1s, leading to extracellular presence of activated C1s. However, the molecular link relating activated C1r and C1s proteases to the dysregulated connective tissue homeostasis in pEDS is unknown. Using cell- and molecular-biological assays, we identified activated C1s (aC1s) as an enzyme which degrades collagen I in cell culture and in in vitro assays. Matrix collagen turnover in cell culture was assessed using labelled hybridizing peptides, which revealed fast and comprehensive collagen protein remodeling in patient fibroblasts. Furthermore, collagen I was completely degraded by aC1s when assays were performed at 40°C, indicating that even moderate elevated temperature has a tremendous impact on collagen I integrity. This high turnover is expected to interfere with the formation of a stable ECM and result in tissues with loose compaction a hallmark of the EDS phenotype. Our results indicate that pathogenesis in pEDS is not solely mediated by activation of the complement cascade but by inadequate C1s-mediated degradation of matrix proteins, confirming pEDS as a primary connective tissue disorder.

Clinical and molecular features of patients with COL1-related disorders: Implications for the wider spectrum and the risk of vascular complications

Abnormalities in type I procollagen genes (COL1A1 and COL1A2) are responsible for hereditary connective tissue disorders including osteogenesis imperfecta (OI), specific types of Ehlers-Danlos syndrome (EDS), and COL1-related overlapping disorder (C1ROD). C1ROD is a recently proposed disorder characterized by predominant EDS symptoms of joint and skin laxity and mild OI symptoms of bone fragility and blue sclera. Patients with C1ROD do not carry specific variants for COL1-related EDS, including classical, vascular, cardiac-valvular, and arthrochalasia types. We describe clinical and molecular findings of 23 Japanese patients with pathogenic or likely pathogenic variants of COL1A1 or COL1A2, who had either OI-like or EDS-like phenotypes. The final diagnoses were OI in 17 patients, classical EDS in one, and C1ROD in five. The OI group predominantly experienced recurrent bone fractures, and the EDS group primarily showed joint hypermobility and skin hyperextensibility, though various clinical and molecular overlaps between OI, COL1-related EDS, and C1ROD as well as intrafamilial phenotypic variabilities were present. Notably, life-threatening vascular complications (vascular dissections, arterial aneurysms, subarachnoidal hemorrhages) occurred in seven patients (41% of those aged >20 years) with OI or C1ROD. Careful lifelong surveillance and intervention regarding bone and vascular fragility could be required.

Next-Generation Sequencing of Connective Tissue Genes in Patients with Classical Ehlers-Danlos Syndrome

Background: Ehlers-Danlos syndrome (EDS) is a common non-inflammatory, congenital connective tissue disorder. Classical type (cEDS) EDS is one of the more common forms, typically caused by mutations in the COL5A1 and COL5A2 genes, though causative mutations in the COL1A1 gene have also been described. Material and methods: The study group included 59 patients of Polish origin, diagnosed with cEDS. The analysis was performed on genomic DNA (gDNA) with NGS technology, using an Illumina sequencer. Thirty-five genes related to connective tissue were investigated. The pathogenicity of the detected variants was assessed by VarSome. Results: The NGS of 35 genes revealed variants within the COL5A1, COL5A2, COL1A1, and COL1A2 genes for 30 of the 59 patients investigated. Our panel detected no sequence variations for the remaining 29 patients. Discussion: Next-generation sequencing, with an appropriate multigene panel, showed great potential to assist in the diagnosis of EDS and other connective tissue disorders. Our data also show that not all causative genes giving rise to cEDS have been elucidated yet.

Osteogenesis Imperfecta/Ehlers-Danlos Overlap Syndrome and Neuroblastoma-Case Report and Review of Literature

Osteogenesis imperfecta/Ehlers−Danlos (OI/EDS) overlap syndrome is a recently described disorder of connective tissue, characterized by mutation of COL1A1 (17q21.33) or COL1A2 (7q21.3) genes, that are involved in α-1 and α-2 chains of type 1 collagen synthesis. The clinical spectrum of this new clinical entity is broad: patients could present a mixed phenotype that includes features of both osteogenesis imperfecta (bone fragility, long bone fractures, blue sclerae, short stature) and Ehlers−Danlos syndrome (joint hyperextensibility, soft and hyperextensible skin, abnormal wound healing, easy bruising, vascular fragility). We reported the case of a young Caucasian girl with severe short stature and a previous history of neuroblastoma, who displayed the compound phenotype of OI/EDS. Next generation sequencing was applied to the proband and her parent genome. Our patient presented a de novo heterozygous COL1A1 variant (c.3235G>A, p.Gly1079Ser), whose presence might be indicative of diagnosis of OI/EDS overlap syndrome. We also hypothesize that the association with the previous history of neuroblastoma could be influenced by the presence of COL1A1 mutation, whose role has been already described in the behavior and progression of some cancers.

A novel pathogenic variant at the C-terminal propeptide cleavage site of COL1A1, causing osteogenesis imperfecta with intrafamilial variability

Osteogenesis imperfecta (OI) is a rare connective tissue disorder with clinical and genetic heterogeneity. The cardinal features of OI are bone fragility and low bone mineral density (BMD). Pathogenic variants in COL1A1 and COL1A2 genes, which encode the proα-1(I) and proα-2(I) chains of Type 1 collagen, are the most common causes of OI. Mutations disrupting the carboxy-terminal propeptide cleavage site of the proα-1(I) and proα-2(I) chains have recently been reported as rare causes of OI with paradoxically normal to high BMD. This report describes a father and daughter with OI who are heterozygous for a novel likely pathogenic variant at the carboxy-terminal propeptide cleavage site of COL1A1 (NM_000088.4): c.3656A>G; (p.Asp1219Gly). We describe their intrafamilial phenotypic variability and overlapping features with other COL1A1-related disorders.

Ehlers-Danlos Syndromes, Joint Hypermobility and Hypermobility Spectrum Disorders

Ehlers-Danlos syndrome is an umbrella term for a clinically and genetically heterogeneous group of hereditary soft connective tissue disorders mainly featuring abnormal cutaneous texture (doughy/velvety, soft, thin, and/or variably hyperextensible skin), easy bruising, and joint hypermobility. Currently, musculoskeletal manifestations related to joint hypermobility are perceived as the most prevalent determinants of the quality of life of affected individuals. The 2017 International Classification of Ehlers-Danlos syndromes and related disorders identifies 13 clinical types due to deleterious variants in 19 different genes. Recent publications point out the possibility of a wider spectrum of conditions that may be considered members of the Ehlers-Danlos syndrome community. Most Ehlers-Danlos syndromes are due to inherited abnormalities affecting the biogenesis of fibrillar collagens and other components of the extracellular matrix. The introduction of next-generation sequencing technologies in the diagnostic setting fastened patients' classification and improved our knowledge on the phenotypic variability of many Ehlers-Danlos syndromes. This is impacting significantly patients' management and family counseling. At the same time, most individuals presenting with joint hypermobility and associated musculoskeletal manifestations still remain without a firm diagnosis, due to a too vague clinical presentation and/or the lack of an identifiable molecular biomarker. These individuals are currently defined with the term "hypermobility spectrum disorders". Hence, in parallel with a continuous update of the International Classification of Ehlers-Danlos syndromes, the scientific community is investing efforts in offering a more efficient framework for classifying and, hopefully, managing individuals with joint hypermobility.

A novel COL1A1 variant in a family with clinical features of hypermobile Ehlers-Danlos syndrome that proved to be a COL1-related overlap disorder

COL1-related overlap disorder is a condition, which is not yet considered as part of the 2017 EDS classification. However, it should be investigated as an alternative diagnosis for any patient with hypermobile EDS. This could allow providing appropriate genetic counseling.

Diversity in heritable disorders of connective tissue at a single center

BACKGROUND

Heritable disorders of connective tissue (HDCT) is a heterogeneous group of conditions caused by defects in genes responsible for extracellular matrix elements. Although next-generation sequencing (NGS) technology can be used to analyze many genes at a time, precisely diagnosing HDCT is still challenging because of the overlapping phenotypes and genotypes.

METHODS

A 67-gene NGS targeted panel or whole-exome sequencing was employed for the diagnosis of HDCT over 4 years. Phenotypes and genotypes of patients were analyzed retrospectively.

RESULTS

Mutations in 16 genes were discovered in 34 patients with the suspicion of Ehlers-Danlos syndrome (n = 7), Marfan syndrome (n = 2), osteogenesis imperfecta (n = 3), skeletal dysplasia (n = 18), and others (n = 4). Eighteen patients were found to have mutations in collagen genes, three had SERPINF1 mutations, two had TRPV4 mutations, two had FBN1 mutations, two had COMP mutations, and mutations in seven other genes were found in one patient each. The eight patients with COL1A1 mutations had a wide variation in phenotype. Patients with COL3A1 and COL5A1 mutations presented with classic EDS, those with SERPINF1 mutations presented with typical OI type VI, those with TRPV4 mutations presented with severe spinal deformity, and those with COL2A1 mutations presented with syndromic or nonsyndromic bone dysplasia or only short stature.

CONCLUSION

A wide diversity in HDCT was observed. Therefore, knowledge about the phenotype-genotype correlation in HDCT is still crucial in the diagnosis of this group of diseases, and an improvement in the screening tool will be needed.

Collagen Fibrillogenesis in the Mitral Valve: It's a Matter of Compliance

Collagen fibers are essential structural components of mitral valve leaflets, their tension apparatus (chordae tendineae), and the associated papillary muscles. Excess or lack of collagen fibers in the extracellular matrix (ECM) in any of these structures can adversely affect mitral valve function. The organization of collagen fibers provides a sophisticated framework that allows for unidirectional blood flow during the precise opening and closing of this vital heart valve. Although numerous ECM molecules are essential for the differentiation, growth, and homeostasis of the mitral valve (e.g., elastic fibers, glycoproteins, and glycans), collagen fibers are key to mitral valve integrity. Besides the inert structural components of the tissues, collagen fibers are dynamic structures that drive outside-to-inside cell signaling, which informs valvular interstitial cells (VICs) present within the tissue environment. Diversity of collagen family members and the closely related collagen-like triple helix-containing proteins found in the mitral valve, will be discussed in addition to how defects in these proteins may lead to valve disease.

Osteogenesis imperfecta in children

Osteogenesis imperfecta (OI) is a disease characterised by altered bone tissue material properties together with abnormal micro and macro-architecture and thus bone fragility, increased bone turnover and hyperosteocytosis. Increasingly appreciated are the soft tissue changes, sarcopenia in particular. Approaches to treatment are now multidisciplinary, with bisphosphonates having been the primary pharmacological intervention over the last 20 years. Whilst meta-analyses suggest that anti-fracture efficacy across the life course is equivocal, there is good evidence that for children bisphosphonates reduce fracture risk, increase vertebral size and improve vertebral shape, as well as improving motor function and mobility. The genetics of OI continues to provide insights into the molecular pathogenesis of the disease, although the pathophysiology is less clear. The complexity of the multi-scale interactions of bone tissue with cellular function are gradually being disentangled, but the fundamental question of why increased tissue brittleness should be associated with so many other changes is unclear; ER stress, pro-inflammatory cytokines, accelerated senesence and altered matrix component release might all contribute, but a unifying hypothesis remains elusive. New approaches to therapy are focussed on increasing bone mass, following the paradigm established by the treatment of postmenopausal osteoporosis. For adults, this brings the prospect of restoring previously lost bone - for children, particularly at the severe end of the spectrum, the possibility of further reducing fracture frequency and possibly altering growth and long term function are attractive. The alternatives that might affect tissue brittleness are autophagy enhancement (through the removal of abnormal type I collagen aggregates) and stem cell transplantation - both still at the preclinical stage of assessment. Preclinical assessment is not supportive of targeting inflammatory pathways, although understanding why TGFb signalling is increased, and whether that presents a treatment target in OI, remains to be established.

Fetal Fractures in an Infant with Maternal Ehlers-Danlos Syndrome, CCDC134 Pathogenic Mutation and a Negative Genetic Test for Osteogenesis Imperfecta

Intrauterine fractures are a rare clinical finding caused by abnormal early-life osteogenesis. In this case report, we reported a male infant with twenty-three intrauterine/fetal fractures resembling osteogenesis imperfecta and tested negative for COL1A1 and COL1A2 mutations. The infant’s mother had Ehlers–Danlos syndrome, hypermobility type. Whole-genome sequencing revealed that there were no pathologic mutations previously documented to be associated with intrauterine fracture. Genetic mutations reported to be associated with fragility fractures were identified. These include the pathogenic homozygous mutation in the CCDC134 gene. Other genetic variants that might be responsible for variable expressivity of the skeletal manifestation include the homozygous variants of the genes CCDC134, COL15A1 and ZFPM1, and the heterozygous variants of the genes MYH3, BCHE, AUTS2. This is the first reported case of in utero fractures, that was confirmed by X-ray after birth, in an infant who had no genetic evidence for osteogenesis imperfecta, had a homozygous pathogenic mutation of an osteogenesis gene and whose mother had Ehlers-Danlos syndrome hypermobility type. Therefore, we have identified a new genetic cause for in utero fractures. If after birth, this infant were found to have these fractures in various stages of healing with a negative genetic test for osteogenesis imperfecta he would have been misdiagnosed as due to nonaccidental trauma.

COL1-Related Disorders: Case Report and Review of Overlapping Syndromes

Collagen type I mutations are related to wide phenotypic expressions frequently causing an overlap of clinical manifestations, in particular between Osteogenesis Imperfecta (OI) and Ehlers-Danlos syndrome (EDS). Both disorders present inter- and intra-familial clinical variability and several clinical signs are present in both diseases. Recently, after the observation that some individuals first ascertained by a suspicion of EDS resulted then carriers of pathogenic variants of genes known to primarily cause OI, some authors proposed the term "COL1-related overlap disorder" to describe these cases. In this paper, we report clinical, molecular, and biochemical information about an individual with a diagnosis of EDS with severe joint hypermobility who carries a pathogenic heterozygous variant in COL1A2 gene, and a benign variant in COL1A1 gene. The pathogenic variant, commonly ascribed to OI, as well as the benign variant, has been inherited from the individual's mother, who presented only mild signs of OI and the diagnosis of OI was confirmed only after molecular testing. In addition, we reviewed the literature of similar cases of overlapping syndromes caused by COL1 gene mutations. The reported case and the literature review suggest that the COL1-related overlap disorders (OI, EDS and overlapping syndromes) represent a continuum of clinical phenotypes related to collagen type I mutations. The spectrum of COL1-related clinical manifestations, the pathophysiology and the underlying molecular mechanisms support the adoption of the updated proposed term "COL1-related overlap disorder" to describe the overlapping syndromes.

Ehlers-Danlos syndrome: what the radiologist needs to know

Ehlers-Danlos syndrome is a real diagnosis that is erroneously used to explain multiple fractures in suspected child abuse. This paper reviews the clinical and molecular diagnostic criteria for Ehlers-Danlos syndrome. This knowledge can help prevent misdiagnosis and support clinicians when evaluating infants and young children with multiple fractures.

Prepubertal Periodontitis in a Patient with Combined Classical and Periodontal Ehlers-Danlos Syndrome

We report an extremely rare case of combined classical and periodontal Ehlers−Danlos syndrome (EDS) with early severe periodontitis and a generalized lack of attached gingiva. A German family with classical EDS was investigated by physical and dental evaluation and exome and Sanger sequencing. Due to the specific periodontal phenotype in the affected child, an additional diagnosis of periodontal EDS was suspected. Physical and genetic examination of two affected and three unaffected family members revealed a family diagnosis of classical EDS with a heterozygous mutation in COL5A1 (c.1502del; p.Pro501Leufs*57). Additional to the major clinical criteria for classical EDS—generalized joint hypermobility, hyperelastic skin, and atrophic scarring —the child aged four years presented with generalized alveolar bone loss up to 80%, early loss of two lower incisors, severe gingival recession, and generalized lack of attached gingiva. Due to these clinical findings, an additional diagnosis of periodontal EDS was suspected. Further genetic analysis revealed the novel missense mutation c.658T>G (p.Cys220Gly) in C1R in a heterozygous state. Early severe periodontitis in association with generalized lack of attached gingiva is pathognomonic for periodontal EDS and led to the right clinical and genetic diagnosis in the present case.

Prospective clinical investigations of children with periodontal Ehlers-Danlos syndrome identify generalized lack of attached gingiva as a pathognomonic feature

PURPOSE

We report prospective clinical investigations of children affected with periodontal Ehlers-Danlos syndrome (pEDS). The main clinical features of pEDS in adults are early severe periodontitis, generalized lack of attached gingiva, and pretibial hemosiderin plaques due to dominant pathogenic variants in the C1R or C1S genes.

METHODS

Nineteen children with a parent diagnosed with molecularly confirmed pEDS underwent physical examination including oral and radiological investigations followed by genetic testing.

RESULTS

The only consistent manifestation of pEDS in childhood was a characteristic gingival phenotype: generalized lack of attached gingiva. All children with this gingival phenotype had inherited the familial pathogenic variant (n = 12) whereas the gingival phenotype was absent in children without the familial pathogenic variant (n = 7). Easy bruising was reported in eight affected and zero unaffected children. Other manifestations of pEDS were rarely present in children. Only 2/12 affected children aged 8 and 13 years fulfilled the clinical criteria for pEDS.

CONCLUSION

Generalized lack of attached gingiva is a pathognomonic feature of pEDS and the only clinical finding that is consistently present in affected adults and children. This is important because an early diagnosis may facilitate better dental hygiene in childhood, which may be essential to prevent early dental loss.

Multisystemic manifestations in a cohort of 75 classical Ehlers-Danlos syndrome patients: natural history and nosological perspectives

Background

The Ehlers-Danlos syndromes (EDS) are rare connective tissue disorders consisting of 13 subtypes with overlapping features including joint hypermobility, skin and generalized connective tissue fragility. Classical EDS (cEDS) is principally caused by heterozygous COL5A1 or COL5A2 variants and rarely by the COL1A1 p.(Arg312Cys) substitution. Current major criteria are (1) skin hyperextensibility plus atrophic scars and (2) generalized joint hypermobility (gJHM). Minor criteria include additional mucocutaneous signs, epicanthal folds, gJHM complications, and an affected first-degree relative. Minimal criteria prompting molecular testing are major criterion 1 plus either major criterion 2 or 3 minor criteria. In addition to these features, the clinical picture also involves multiple organ systems, but large-scale cohort studies are still missing. This study aimed to investigate the multisystemic involvement and natural history of cEDS through a cross-sectional study on a cohort of 75 molecularly confirmed patients evaluated from 2010 to 2019 in a tertiary referral center. The diagnostic criteria, additional mucocutaneous, osteoarticular, musculoskeletal, cardiovascular, gastrointestinal, uro-gynecological, neuropsychiatric, and atopic issues, and facial/ocular features were ascertained, and feature rates compared by sex and age.

Results

Our study confirms that cEDS is mainly characterized by cutaneous and articular involvement, though none of their hallmarks was represented in all cases and suggests a milder multisystemic involvement and a more favorable natural history compared to other EDS subtypes. Abnormal scarring was the most frequent and characteristic sign, skin hyperextensibility and gJHM were less common, all without any sex and age bias; joint instability complications were more recurrent in adults. Some orthopedic features showed a high prevalence, whereas the other issues related to the investigated organ systems were less recurrent with few exceptions and age-related differences.

Conclusions

Our findings define the diagnostic relevance of cutaneous and articular features and additional clinical signs associated to cEDS. Furthermore, our data suggest an update of the current EDS nosology concerning scarring that should be considered separately from skin hyperextensibility and that the clinical diagnosis of cEDS may be enhanced by the accurate evaluation of orthopedic manifestations at all ages, faciocutaneous indicators in children, and some acquired traits related to joint instability complications, premature skin aging, and patterning of abnormal scarring in older individuals.

The Ehlers-Danlos syndromes

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of hereditary disorders of connective tissue, with common features including joint hypermobility, soft and hyperextensible skin, abnormal wound healing and easy bruising. Fourteen different types of EDS are recognized, of which the molecular cause is known for 13 types. These types are caused by variants in 20 different genes, the majority of which encode the fibrillar collagen types I, III and V, modifying or processing enzymes for those proteins, and enzymes that can modify glycosaminoglycan chains of proteoglycans. For the hypermobile type of EDS, the molecular underpinnings remain unknown. As connective tissue is ubiquitously distributed throughout the body, manifestations of the different types of EDS are present, to varying degrees, in virtually every organ system. This can make these disorders particularly challenging to diagnose and manage. Management consists of a care team responsible for surveillance of major and organ-specific complications (for example, arterial aneurysm and dissection), integrated physical medicine and rehabilitation. No specific medical or genetic therapies are available for any type of EDS.

Identification of the novel COL5A1 c.3369_3431dup, p.(Glu1124_Gly1144dup) variant in a patient with incomplete classical Ehlers-Danlos syndrome: The importance of phenotype-guided genetic testing

Background

Classical Ehlers–Danlos syndrome (cEDS) is a connective tissue disorder mainly caused by heterozygous COL5A1 or COL5A2 variants encoding type V collagen and rarely by the p.(Arg312Cys) missense substitution in COL1A1 encoding type I collagen. The current EDS nosology specifies that minimal suggestive criteria are marked skin hyperextensibility plus atrophic scarring together with either generalized joint hypermobility or at least three minor criteria comprising additional cutaneous and articular signs. To reach a final diagnosis, molecular testing is required. Herein, we report on a 3‐year‐old female who came to our attention with an inconclusive next generation sequencing (NGS) panel comprising all cEDS‐associated genes.

Methods

Despite the patient did not formally fulfill the nosological criteria because the skin was only slightly hyperextensible, we made a cEDS diagnosis, mainly for the presence of typical atrophic scars. We investigated COL5A1 intragenic deletions/duplications by Multiplex Ligation‐dependent Probe Amplification (MLPA), excluded the recessive classical‐like EDS type 2 by AEBP1 Sanger analysis, and retested COL5A1 with the Sanger method.

Results

Molecular analyses revealed the novel COL5A1 c.3369_3431dup p.(Glu1124_Gly1144dup) intermediate‐sized duplication with a predicted dominant negative effect that was missed both by NGS and MLPA.

Conclusions

This report highlights that some cEDS patients might not display overt skin hyperextensibility and the importance of clinical expertise to make such a diagnosis in patients with an incomplete presentation. Our results also exemplify that NGS is not a fool‐proof technology and that Sanger sequencing achieves the diagnostic goal when there is a sufficiently clear phenotypic indication.