Hypermobile Ehlers-Danlos syndrome: A review and a critical appraisal of published genetic research to date.

The Ehlers-Danlos syndromes (EDS) are a collection of rare hereditary connective tissue disorders with heterogeneous phenotypes, usually diagnosed following clinical examination and confirmatory genetic testing. Diagnosis of the commonest subtype, hypermobile Ehlers-Danlos Syndrome (hEDS), relies solely on a clinical diagnosis since its molecular aetiology remains unknown. We performed an up-to-date literature search and selected 11 out of 304 publications according to a set of established criteria. Studies reporting variants affecting collagen proteins were found to be hindered by cohort misclassification and subsequent lack of reproducibility of these genetic findings. The role of the described variants affecting Tenascin-X and LZTS1 is yet to be demonstrated in the majority of hEDS cases, while the functional implication of associated signaling pathways and genes requires further elucidation. The available literature on the genetics of hEDS is scant, dispersed and conflicting due to out-dated nosology terminology. Recent literature has suggested the role of several promising candidate mechanisms which may be linked to the underlying molecular aetiology. Knowledge of the molecular genetic basis of hEDS is expected to increase in the near future through the mainstream use of high-throughput sequencing combined with the updated classification of EDS, and the upcoming Hypermobile Ehlers-Danlos Genetic Evaluation (HEDGE) study.

Deconstructing and reconstructing joint hypermobility on an evo-devo perspective.

Joint hypermobility is a common characteristic in humans. Its non-casual association with various musculoskeletal complaints is known and currently defined "the spectrum". It includes hypermobile Ehlers-Danlos syndrome (hEDS) and hypermobility spectrum disorders (HSD). hEDS is recognized by a set of descriptive criteria, while HSD is the background diagnosis for individuals not fulfilling these criteria. Little is known about the aetiopathogenesis of the spectrum. It may be interpreted as a complex trait according to the integration model. Particularly, the spectrum is common in the general population, affects morphology, presents extreme clinical variability and is characterized by marked sex bias without a clear Mendelian or hormonal explanation. Joint hypermobility and the other hEDS systemic criteria are intended as qualitative derivatives of continuous traits of normal morphological variability. The need for a minimum set of criteria for hEDS diagnosis implies a tendency to co-vary of these underlying continuous traits. In evolutionary biology, such a co-variation (i.e. integration) is driven by multiple forces, including genetic, developmental, functional and environmental/acquired interactors. The aetiopathogenesis of the spectrum may be resolved by a deeper understanding of phenotypic variability, which superimposes on normal morphological variability.

Periodontal (formerly type VIII) Ehlers-Danlos syndrome: Description of 13 novel cases and expansion of the clinical phenotype.

Periodontal Ehlers-Danlos syndrome (pEDS) is a rare condition caused by pathogenic variants in the C1R and C1S genes, encoding subunits C1r and C1s of the first component of the classical complement pathway. It is characterized by early-onset periodontitis with premature tooth loss, pretibial hyperpigmentation and skin fragility. Rare arterial complications have been reported, but venous insufficiency is rarely described. Here we report 13 novel patients carrying heterozygous pathogenic variants in C1R and C1S including three novel C1S variants (c.962G > C, c.961 T > G and c.961 T > A). In addition to the pEDS phenotype, three patients and one relative displayed widespread venous insufficiency leading to persistent varicose leg ulcers. One patient suffered an intracranial aneurysm with familial vascular complications including thoracic and abdominal aortic aneurysm and dissection and intracranial aneurysm rupture. This work confirms that vascular complications can occur, although they are not frequent, which leads us to propose to carry out a first complete non-invasive vascular evaluation at the time of the diagnosis in pEDS patients. However, larger case series are needed to improve our understanding of the link between complement pathway activation and connective tissue alterations observed in these patients, and to better assess the frequency, type and consequences of the vascular complications.

Natural history and manifestations of the hypermobility type Ehlers-Danlos syndrome: a pilot study on 21 patients.

Hypermobility type Ehlers-Danlos syndrome (HT-EDS) is a relatively frequent, although commonly misdiagnosed variant of Ehlers-Danlos syndrome, mainly characterized by marked joint instability and mild cutaneous involvement. Chronic pain, asthenia, and gastrointestinal and pelvic dysfunction are characteristic additional manifestations. We report on 21 HT-EDS patients selected from a group of 40 subjects with suspected mild hereditary connective tissue disorder. General, mucocutaneous, musculoskeletal, cardiovascular, neurologic, gastrointestinal, urogynecological, and ear-nose-throat abnormalities are investigated systematically and tabulated. Six distinct clinical presentations of HT-EDS are outlined, whose tabulation is a mnemonic for the practicing clinical geneticist in an attempt to diagnose this condition accurately. With detailed clinical records and phenotype comparison among patients of different ages, the natural history of the disorder is defined. Three phases (namely, hypermobility, pain, and stiffness) are delineated based on distinguishing manifestations. A constellation of additional, apparently uncommon abnormalities is also identified, including dolichocolon, dysphonia, and Arnold-Chiari type I malformation. Their further investigation may contribute to an understanding of the pathogenesis of the protean manifestations of HT-EDS, and a more effective approach to the evaluation and management of affected individuals.

Cellular and Molecular Mechanisms in the Pathogenesis of Classical, Vascular, and Hypermobile Ehlers‒Danlos Syndromes.

The Ehlers‒Danlos syndromes (EDS) constitute a heterogenous group of connective tissue disorders characterized by joint hypermobility, skin abnormalities, and vascular fragility. The latest nosology recognizes 13 types caused by pathogenic variants in genes encoding collagens and other molecules involved in collagen processing and extracellular matrix (ECM) biology. Classical (cEDS), vascular (vEDS), and hypermobile (hEDS) EDS are the most frequent types. cEDS and vEDS are caused respectively by defects in collagen V and collagen III, whereas the molecular basis of hEDS is unknown. For these disorders, the molecular pathology remains poorly studied. Herein, we review, expand, and compare our previous transcriptome and protein studies on dermal fibroblasts from cEDS, vEDS, and hEDS patients, offering insights and perspectives in their molecular mechanisms. These cells, though sharing a pathological ECM remodeling, show differences in the underlying pathomechanisms. In cEDS and vEDS fibroblasts, key processes such as collagen biosynthesis/processing, protein folding quality control, endoplasmic reticulum homeostasis, autophagy, and wound healing are perturbed. In hEDS cells, gene expression changes related to cell-matrix interactions, inflammatory/pain responses, and acquisition of an in vitro pro-inflammatory myofibroblast-like phenotype may contribute to the complex pathogenesis of the disorder. Finally, emerging findings from miRNA profiling of hEDS fibroblasts are discussed to add some novel biological aspects about hEDS etiopathogenesis.

High-Throughput Screening for CYP21A1P-TNXA/TNXB Chimeric Genes Responsible for Ehlers-Danlos Syndrome in Patients with Congenital Adrenal Hyperplasia.

Many patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency have CAH-X syndrome, a connective tissue dysplasia consistent with hypermobility-type Ehlers-Danlos syndrome due to a contiguous gene deletion involving the adjacent CYP21A2 and TNXB genes. CAH-X syndrome is caused by carrying CYP21A1P-TNXA/TNXB chimeric genes [CAH-X chimera 1 (CH-1) and chimera 2 (CH-2)] on one or more alleles. Genetic analysis is cumbersome due to pseudogene interference. We developed a PCR-based CAH-X high-throughput screening method to assess the copy numbers of TNXB exons 35 and 40; this method is amenable to either real-time quantitative PCR or droplet digital PCR (ddPCR). The assay was validated in a cohort of 278 subjects from 146 unrelated CAH families. Results were confirmed by a validated Sanger sequencing platform. A total of 44 CAH-X-positive calls were made, with 42 (26 CH-1 and 16 CH-2) confirmed. The assay had 100% sensitivity (42 true/42 positives), 99.2% specificity (234 true/236 negatives), and an overall 99.3% accuracy (276/278). Calls made by real-time quantitative PCR and ddPCR were consistent (100%), and ddPCR offered easier data interpretation. The CAH-X prevalence was 15.6% (21/135 probands), higher than the previously estimated 8.5%, and was particularly high (29.2% or 21/72) in those with a 30-Kb deletion. This assay is suitable for high-throughput CAH-X screening, especially in subjects testing positive for CAH in neonatal screening.

Ehlers-Danlos syndrome type IV with gastric adenocarcinoma.

BACKGROUND: Ehlers-Danlos syndrome has many subtypes. The vascular type (type IV) is characterized by thin, translucent skin, easy bruising, characteristic facial appearance, and arterial, intestinal, and/or uterine fragility. OBJECTIVES: To encourage a better understanding of vascular EDS as a basis for early diagnosis, prevention, and management of complications. A first case of EDS type IV with adeno-carcinoma of the stomach in Thailand was reported and literature was reviewed. RESULT: A 62-year-old Thai priest was admitted in Priest Hospital because of progressive muscle weakness of both legs with neurogenic claudication from compression fracture of L1-2. Abdominal aortic aneurysm were detected with upper gastrointestinal hemorrhage, esophagogastroduodenoscopy showed diffuse gastric body swelling and erythema resulting in chronic gastritis. Gastric biopsy was indicative of adenocarcinoma of the stomach and gastrectomy was done. Dermatologists were consulted due to generalized cutaneous pain, easy bruising following venepuncture, and EKG padding. A vascular EDS type IV was diagnosed. CONCLUSION: After gastrectomy, the patient became drowsy and unconscious from profuse recurrent cerebral hemorrhage and expired.

Craniofacial abnormality with skeletal dysplasia in mice lacking chondroitin sulfate N-acetylgalactosaminyltransferase-1.

Chondroitin sulfate (CS) proteoglycan is a major component of the extracellular matrix and plays an important part in organogenesis. To elucidate the roles of CS for craniofacial development, we analyzed the craniofacial morphology in CS N-acetylgalactosaminyltransferase-1 (T1) gene knockout (KO) mice. T1KO mice showed the impaired intramembranous ossification in the skull, and the final skull shape of adult mice included a shorter face, higher and broader calvaria. Some of T1KO mice exhibited severe facial developmental defect, such as eye defects and cleft lip and palate, causing embryonic lethality. At the postnatal stages, T1KO mice with severely reduced CS amounts showed malocclusion, general skeletal dysplasia and skin hyperextension, closely resembling Ehlers-Danlos syndrome-like connective tissue disorders. The production of collagen type 1 was significantly downregulated in T1KO mice, and the deposition of CS-binding molecules, Wnt3a, was decreased with CS in extracellular matrices. The collagen fibers were irregular and aggregated, and connective tissues were dysorganized in the skin and calvaria of T1KO mice. These results suggest that CS regulates the shape of the craniofacial skeleton by modulating connective tissue organization and that the remarkable reduction of CS induces hypoplasia of intramembranous ossification and cartilage anomaly, resulting in skeletal dysplasia.

Transcriptome analysis of skin fibroblasts with dominant negative COL3A1 mutations provides molecular insights into the etiopathology of vascular Ehlers-Danlos syndrome.

Vascular Ehlers-Danlos syndrome (vEDS) is a dominantly inherited connective tissue disorder caused by mutations in the COL3A1 gene that encodes type III collagen (COLLIII), which is the major expressed collagen in blood vessels and hollow organs. The majority of disease-causing variants in COL3A1 are glycine substitutions and in-frame splice mutations in the triple helix domain that through a dominant negative effect are associated with the severe clinical spectrum potentially lethal of vEDS, characterized by fragility of soft connective tissues with arterial and organ ruptures. To shed lights into molecular mechanisms underlying vEDS, we performed gene expression profiling in cultured skin fibroblasts from three patients with different structural COL3A1 mutations. Transcriptome analysis revealed significant changes in the expression levels of several genes involved in maintenance of cell redox and endoplasmic reticulum (ER) homeostasis, COLLs folding and extracellular matrix (ECM) organization, formation of the proteasome complex, and cell cycle regulation. Protein analyses showed that aberrant COLLIII expression is associated with the disassembly of many structural ECM constituents, such as fibrillins, EMILINs, and elastin, as well as with the reduction of the proteoglycans perlecan, decorin, and versican, all playing an important role in the vascular system. Furthermore, the altered distribution of the ER marker protein disulfide isomerase PDI and the strong reduction of the COLLs-modifying enzyme FKBP22 are consistent with the disturbance of ER-related homeostasis and COLLs biosynthesis and post-translational modifications, indicated by microarray analysis. Our findings add new insights into the pathophysiology of this severe vascular disorder, since they provide a picture of the gene expression changes in vEDS skin fibroblasts and highlight that dominant negative mutations in COL3A1 also affect post-translational modifications and deposition into the ECM of several structural proteins crucial to the integrity of soft connective tissues.

Collagen dysregulation in the dermis of the Sagg/+ mouse: a loose skin model.

The Sagg/+ mouse is an ethylnitrosourea-derived mutant with a dermal phenotype similar to some of the subtypes of Ehlers-Danlos syndrome (EDS) and cutis laxa. The dermis of the Sagg/+ mouse has less dense and more disorganized collagen fibers compared to controls. The size of extracted Type I dermal collagen was the same as that observed in normal skin; however, more collagen could be extracted from Sagg/+ skin, which also showed decreased collagen content and decreased steady-state levels of alpha1(I), alpha2(I), alpha1(V), and alpha2(V) procollagen mRNAs. The biomechanical properties of Sagg/+ skin were significantly decreased relative to normal skin. However, there were no significant differences in the quantities of the major collagen cross-links, that is, dehydrohydroxylysinonorleucine and dehydrohistidinohydroxymerodesmosine between Sagg/+ and normal skin. Electron microscopic evaluation of Sagg/+ skin indicated that the mutation interferes with the proper formation of collagen fibrils and the data are consistent with a mutation in Type V collagen leading to haploinsufficiency with the formation of two sub-populations of collagen fibrils, one normal and one with irregular shape and a larger diameter. Further study of this novel mutation will allow the identification of new mechanisms involved in the regulation of normal and pathologic collagen gene expression.

[Skin collagen abnormalities in a Japanese patient with extracranial internal carotid artery dissection followed by extracranial vertebral artery dissection].

A 41-year-old man with hypertension and hyperlipidemia who complained of left hemiparesis after a temporal headache was admitted to our hospital. A cervical MRI with gadolinium enhancement revealed an intramural hematoma is compatible with right extracranial internal carotid artery dissection. Two weeks later, he complained of sudden onset of pain in the right side of his neck. The right extracranial internal carotid artery dissection followed by the right extracranial vertebral artery dissection was diagnosed. Spontaneous cervical artery dissection (SCAD) is one of the causes of stroke in young adults. The pathogenesis of SCAD remains unknown. Minor trauma like an excessive sneeze, migraine, and connective tissue disorders such as fibromuscular dysplasia and Ehlers-Danlos syndrome are well-known as risk factors for SCAD. Pathologically skin collagen abnormalities have been seen in German patients with SCAD without clinical evidence for any specific connective tissue disorder. We examined the ultrastructural morphology of the Japanese patient's dermal connective tissue components by electron microscopy. The patient's collagen fibers contained fibrils with highly variable diameters, and there were other ultrastructural abnormalities, including flower-like fibrils and large-diameter composite fibrils. This is the first report of a case of ultrastructural abnormalities of dermal connective tissue in a Japanese patient with SCAD.

The Expanding Clinical Spectrum of Extracardiovascular and Cardiovascular Manifestations of Heritable Thoracic Aortic Aneurysm and Dissection.

More than 30 heritable conditions are associated with thoracic aortic aneurysm and dissection (TAAD). Heritable syndromic conditions, such as Marfan syndrome, Loeys-Dietz syndrome, and vascular Ehlers-Danlos syndrome, have somewhat overlapping systemic features, but careful clinical assessment usually enables a diagnosis that can be validated with genetic testing. Nonsyndromic FTAAD can also occur and in 20%-25% of these probands mutations exist in genes that encode elements of the extracellular matrix, signalling pathways (especially involving transforming growth factor-ß), and vascular smooth muscle cytoskeletal and contractile processes. Affected individuals with either a syndromic presentation or isolated TAAD can have mutations in the same gene. In this review we focus on the genes currently known to have causal mutations for syndromic and isolated FTAAD and outline the range of associated extracardiovascular and cardiovascular manifestations with each.

Cutaneous asthenia (Ehlers-Danlos-like syndrome) of Burmese cats.

OF CASES: A 6-month-old Burmese kitten developed focal skin lesions following a routine ovariohysterectomy. These were eventually attributed to the patient struggling during catheter placement and induction of anaesthesia. The lesions were caused by fluid extravasation in the subcutis and ischaemic necrosis of the overlying dermis, giving rise to an eschar-like appearance. Such lesions have been seen previously in Burmese cats with cutaneous asthenia and it is thought that they arise due to poor collagenous support for dermal blood vessels. An increased skin extensibility index (>23%) supported a diagnosis of cutaneous asthenia (Ehlers-Danlos-like syndrome), which has been reported as an inherited condition of Burmese cats in Australia, New Zealand and Europe. An additional Burmese cat with cutaneous asthenia is presented in detail, with lifetime follow-up and further salient observations by the owner, a veterinarian. Photographs of three other affected Burmese cats are provided to illustrate the range of presentations encountered with this condition. All five affected cats were presented with eschars, atrophic alopecia and increased skin extensibility, while one cat also had skin ulcers. Routine histopathological examination, including use of special stains such as trichrome, was unhelpful in establishing the diagnosis. CLINICAL REVIEW: The clinical features of this genetic disease of Burmese cats are reviewed, especially in relation to the postulated 'vasculopathy' that gives rise to characteristic skin lesions. Long term management of this condition is discussed briefly.

Phenotypic effects of biglycan deficiency are linked to collagen fibril abnormalities, are synergized by decorin deficiency, and mimic Ehlers-Danlos-like changes in bone and other connective tissues.

Decorin (dcn) and biglycan (bgn), two members of the family of small leucine-rich proteoglycans (SLRPs), are the predominant proteoglycans expressed in skin and bone, respectively. Targeted disruption of the dcn gene results in skin laxity and fragility, whereas disruption of the bgn gene results in reduced skeletal growth and bone mass leading to generalized osteopenia, particularly in older animals. Here, we report that bgn deficiency leads to structural abnormality in collagen fibrils in bone, dermis, and tendon, and to a "subclinical" cutaneous phenotype with thinning of the dermis but without overt skin fragility. A comparative ultrastructural study of different tissues from bgn- and dcn-deficient mice revealed that bgn and dcn deficiency have similar effects on collagen fibril structure in the dermis but not in bone. Ultrastructural and phenotypic analysis of newly generated bgn/dcn double-knockout (KO) mice revealed that the effects of dcn and bgn deficiency are additive in the dermis and synergistic in bone. Severe skin fragility and marked osteopenia characterize the phenotype of double-KO animals in which progeroid changes are observed also in the skin. Ultrastructural analysis of bone collagen fibrils in bone of double-KO mice reveals a complete loss of the basic fibril geometry with the emergence of marked "serrated fibril" morphology. The phenotype of the double-KO animal mimics directly the rare progeroid variant of human Ehlers-Danlos syndrome (EDS), in which skin fragility, progeroid changes in the skin (reduced hypodermis), and osteopenia concur as a result of impaired glycosaminoglycan (GAG) linking to bgn and dcn core proteins. Our data show that changes in collagen fibril morphology reminiscent of those occurring in the varied spectrum of human EDS are induced by both bgn deficiency and den deficiency in mice. The effects of an individual SLRP deficiency are tissue specific, and the expression of a gross phenotype depends on multiple variables including level of expression of individual SLRPs in different tissues and synergisms between different SLRPs (and likely other macromolecules) in determining matrix structure and functional properties.

Diseases of aberrant glycosylation.

Recently a defective glycosylation of glycoconjugates has been implicated in the pathogenesis of a number of heritable or acquired diseases of humans. Herein I discuss them under the name of diseases of aberrant glycosylation. These are: congenital dyserythropoietic anemia type II, carbohydrate-deficient glycoprotein syndrome, I-cell disease, galactosemia in subjects on galactose-free diet, variants of leukocyte adhesion deficiency, and of Ehlers-Danlos syndrome, paroxysmal nocturnal hemoglobinuria, and Tn syndrome. Regarding the present views on the function of glycoconjugates it is probably significant that in most instances defective or missing glycoproteins (or proteoglycans) but not glycosphingolipids, are probably involved in the pathogenesis of these diseases.

The formation of collagen and its relation to ophthalmic diseases (second of two parts).

In this second part of the review the chemical abnormalities that have resulted in the formation of detective collagen and consequent disease of the eye are indicated. The cardinal findings for each disease are noted. Certain changes, such as ageing, that relate to collagen are also discussed.

The natural history of human dermatosparaxis (Ehlers-Danlos syndrome type VIIC).

Dermatosparaxis (Ehlers-Danlos syndrome type VIIC) has only recently been identified in human subjects. Although well documented in animals, to date only three human cases have been recorded, all aged 2 years or under. We document a 15-year-old girl with this newly recognized condition to emphasize the remarkable similarity of physical signs in all four cases. The striking skin fragility which attends the phenotype is highly distinctive, so that the diagnosis may be suspected on clinical grounds. The confirmatory diagnostic procedures are discussed.