Targeted next-generation sequencing makes new molecular diagnoses and expands genotype–phenotype relationship in Ehlers–Danlos syndrome

Novel COL5A1 variants and associated disease phenotypes in dogs with classical Ehlers-Danlos syndrome

BACKGROUND

Human patients with Ehlers-Danlos syndrome (EDS) are categorized into subtypes based on causative genetic variants and phenotypes. The classical form of EDS, primarily caused by variants in COL5A1 or COL5A2, is a very common subtype in people but is poorly characterized in dogs.

OBJECTIVE

Describe likely causal COL5A1 variants in dogs with classical EDS, summarize clinical histories, discuss potential disease mechanisms, and draw conclusions about disease prognosis.

ANIMALS

Seven client-owned dogs that exhibited clinical signs of classical EDS.

METHODS

Clinical information was recorded from medical records and communication with attending veterinarians and dog owners. To identify potential causal gene sequence variants whole-genome sequence analyses (n = 6) or Sanger sequencing (n = 1) were performed on DNA isolated from the probands. Pathological abnormalities in skin biopsy samples were assessed using histology and electron microscopy in 3 dogs.

RESULTS

Six distinct heterozygous COL5A1 sequence variants were identified. The most common clinical signs included fragile skin (n = 7), hyperextensible skin (n = 7), joint hypermobility (n = 6), and atrophic scars (n = 5). The median age at last follow-up or death was 12 years (range, 6.5-14 years). Ultrastructural abnormalities in dermal collagen differed among dogs with different COL5A1 variants.

CONCLUSION AND CLINICAL IMPORTANCE

We describe the genotypic and phenotypic spectrum of the classical subtype of EDS by identifying 6 novel COL5A1 variants in conjunction with detailed clinical histories that included long-term follow-up information in 7 dogs.

Implementation of multiomic mass spectrometry approaches for the evaluation of human health following environmental exposure

Omics analyses collectively refer to the possibility of profiling genetic variants, RNA, epigenetic markers, proteins, lipids, and metabolites. The most common analytical approaches used for detecting molecules present within biofluids related to metabolism are vibrational spectroscopy techniques, represented by infrared, Raman, and nuclear magnetic resonance (NMR) spectroscopies and mass spectrometry (MS). Omics-based assessments utilizing MS are rapidly expanding and being applied to various scientific disciplines and clinical settings. Most of the omics instruments are operated by specialists in dedicated laboratories; however, the development of miniature portable omics has made the technology more available to users for field applications. Variations in molecular information gained from omics approaches are useful for evaluating human health following environmental exposure and the development and progression of numerous diseases. As MS technology develops so do statistical and machine learning methods for the detection of molecular deviations from personalized metabolism, which are correlated to altered health conditions, and they are intended to provide a multi-disciplinary overview for researchers interested in adding multiomic analysis to their current efforts. This includes an introduction to mass spectrometry-based omics technologies, current state-of-the-art capabilities and their respective strengths and limitations for surveying molecular information. Furthermore, we describe how knowledge gained from these assessments can be applied to personalized medicine and diagnostic strategies.

Clinical-Genomic Analysis of 1261 Patients with Ehlers-Danlos Syndrome Outlines an Articulo-Autonomic Gene Network (Entome)

Systematic evaluation of 80 history and 40 history findings diagnosed 1261 patients with Ehlers-Danlos syndrome (EDS) by direct or online interaction, and 60 key findings were selected for their relation to clinical mechanisms and/or management. Genomic testing results in 566 of these patients supported EDS relevance by their differences from those in 82 developmental disability patients and by their association with general rather than type-specific EDS findings. The 437 nuclear and 79 mitochondrial DNA changes included 71 impacting joint matrix (49 COL5), 39 bone (30 COL1/2/9/11), 22 vessel (12 COL3/8VWF), 43 vessel-heart (17FBN1/11TGFB/BR), 59 muscle (28 COL6/12), 56 neural (16 SCN9A/10A/11A), and 74 autonomic (13 POLG/25porphyria related). These genes were distributed over all chromosomes but the Y, a network analogized to an 'entome' where DNA change disrupts truncal mechanisms (skin constraint, neuromuscular support, joint vessel flexibility) and produces a mirroring cascade of articular and autonomic symptoms. The implied sequences of genes from nodal proteins to hypermobility to branching tissue laxity or dysautonomia symptoms would be ideal for large language/artificial intelligence analyses.

Genetic complexity of diagnostically unresolved Ehlers-Danlos syndrome

BACKGROUND

The Ehlers-Danlos syndromes (EDS) are heritable disorders of connective tissue (HDCT), reclassified in the 2017 nosology into 13 subtypes. The genetic basis for hypermobile Ehlers-Danlos syndrome (hEDS) remains unknown.

METHODS

Whole exome sequencing (WES) was undertaken on 174 EDS patients recruited from a national diagnostic service for complex EDS and a specialist clinic for hEDS. Patients had already undergone expert phenotyping, laboratory investigation and gene sequencing, but were without a genetic diagnosis. Filtered WES data were reviewed for genes underlying Mendelian disorders and loci reported in EDS linkage, transcriptome and genome-wide association studies (GWAS). A genetic burden analysis (Minor Allele Frequency (MAF) <0.05) incorporating 248 Avon Longitudinal Study of Parents and Children (ALSPAC) controls sequenced as part of the UK10K study was undertaken using TASER methodology.

RESULTS

Heterozygous pathogenic (P) or likely pathogenic (LP) variants were identified in known EDS and Loeys-Dietz (LDS) genes. Multiple variants of uncertain significance where segregation and functional analysis may enable reclassification were found in genes associated with EDS, LDS, heritable thoracic aortic disease (HTAD), Mendelian disorders with EDS symptomatology and syndromes with EDS-like features. Genetic burden analysis revealed a number of novel loci, although none reached the threshold for genome-wide significance. Variants with biological plausibility were found in genes and pathways not currently associated with EDS or HTAD.

CONCLUSIONS

We demonstrate the clinical utility of large panel-based sequencing and WES for patients with complex EDS in distinguishing rare EDS subtypes, LDS and related syndromes. Although many of the P and LP variants reported in this cohort would be identified with current panel testing, they were not at the time of this study, highlighting the use of extended panels and WES as a clinical tool for complex EDS. Our results are consistent with the complex genetic architecture of EDS and suggest a number of novel hEDS and HTAD candidate genes and pathways.

Dermatologic manifestations and diagnostic assessments of the Ehlers-Danlos syndromes: A clinical review

BACKGROUND

The Ehlers-Danlos syndromes (EDSs) comprise a group of connective tissue disorders that manifest with skin hyperextensibility, easy bruising, joint hypermobility and fragility of skin, soft tissues, and some organs. A correct assessment of cutaneous features along with the use of adjunct technologies can improve diagnostic accuracy.

OBJECTIVES

To systematically review the cutaneous features and adjunct investigations of EDS.

METHODS

A search of PubMed and Web of Science for EDS-related cutaneous features and additional investigations was undertaken from publication of the 2017 International Classification of EDS until January 15, 2022.

RESULTS

One-hundred-and-forty studies involved 839 patients with EDS. The EDS female-to-male ratio was 1.36:1 (P < .001). A high prevalence of skin hyperextensibility, bruising, and soft skin were noted. Most patients with vascular Ehlers-Danlos syndrome showed venous visibility, skin fragility, and acrogeria. Classical EDS showed subcutaneous spheroids and molluscoid pseudotumours. In patients that underwent skin biopsies, only 30.3% and 71.4% showed features suggestive of EDS using light microscopy and transmission electron microscopy, respectively.

LIMITATIONS

Retrospective study and small cases numbers for some EDS-subtypes.

CONCLUSIONS

An accurate clinical diagnosis increases the chances of a molecular diagnosis, particularly for rarer EDS subtypes, whilst decreasing the need for genetic testing where there is a low clinical suspicion for a monogenic EDS-subtype.

A Clinical Qualification Protocol Highlights Overlapping Genomic Influences and Neuro-Autonomic Mechanisms in Ehlers-Danlos and Long COVID-19 Syndromes

A substantial fraction of the 15% with double-jointedness or hypermobility have the traditionally ascertained joint-skeletal, cutaneous, and cardiovascular symptoms of connective tissue dysplasia and its particular manifestation as Ehlers-Danlos syndrome (EDS). The holistic ascertainment of 120 findings in 1261 EDS patients added neuro-autonomic symptoms like headaches, muscle weakness, brain fog, chronic fatigue, dyspnea, and bowel irregularity to those of arthralgia and skin laxity, 15 of these symptoms shared with those of post-infectious SARS-CoV-2 (long COVID-19). Underlying articulo-autonomic mechanisms guided a clinical qualification protocol that qualified DNA variants in 317 genes as having diagnostic utility for EDS, six of them identical (F2-LIFR-NLRP3-STAT1-T1CAM1-TNFRSF13B) and eighteen similar to those modifying COVID-19 severity/EDS, including ADAMTS13/ADAMTS2-C3/C1R-IKBKG/IKBKAP-PIK3C3/PIK3R1-POLD4/POLG-TMPRSS2/TMPRSS6-WNT3/WNT10A. Also, contributing to EDS and COVID-19 severity were forty and three genes, respectively, impacting mitochondrial functions as well as parts of an overlapping gene network, or entome, that are hypothesized to mediate the cognitive-behavioral, neuro-autonomic, and immune-inflammatory alterations of connective tissue in these conditions. The further characterization of long COVID-19 natural history and genetic predisposition will be necessary before these parallels to EDS can be carefully delineated and translated into therapies.

Comprehensive genetic screening for vascular Ehlers-Danlos syndrome through an amplification-based next-generation sequencing system

Vascular Ehlers-Danlos syndrome (vEDS) is a hereditary connective tissue disorder (HCTD) characterized by arterial dissection/aneurysm/rupture, sigmoid colon rupture, or uterine rupture. Diagnosis is confirmed by detecting heterozygous variants in COL3A1. This is the largest Asian case series and the first to apply an amplification-based next-generation sequencing through custom panels of causative genes for HCTDs, including a specific method of evaluating copy number variations. Among 429 patients with suspected HCTDs analyzed, 101 were suspected to have vEDS, and 33 of them (32.4%) were found to have COL3A1 variants. Two patients with a clinical diagnosis of Loeys-Dietz syndrome and/or familial thoracic aortic aneurysm and dissection were also found to have COL3A1 variants. Twenty cases (57.1%) had missense variants leading to glycine (Gly) substitutions in the triple helical domain, one (2.9%) had a missense variant leading to non-Gly substitution in this domain, eight (22.9%) had splice site alterations, three (8.6%) had nonsense variants, two (5.7%) had in-frame deletions, and one (2.9%) had a multi-exon deletion, including two deceased patients analyzed with formalin-fixed and paraffin-embedded samples. This is a clinically useful system to detect a wide spectrum of variants from various types of samples.

Next-generation sequencing and analysis of consecutive patients referred for connective tissue disorders

Heritable connective tissue disorders (HCTDs) consist of a wide array of genetic disorders such as Ehlers-Danlos syndrome, Marfan syndrome, and osteogenesis imperfecta. The diagnosis relies on clinical presentation and family history to guide genetic testing with next-generation sequencing (NGS) for identification of gene variants in HCTDs. NGS was performed on a cohort of 100 consecutive, unrelated patients referred for a connective tissue disorder at Fulgent Genetics, an accredited commercial laboratory. One hundred seventeen gene variants were found in 76 patients with 10 recognized pathogenic or likely pathogenic variants seen in nine patients. The remaining variants were grouped as unknown clinical significance with 36 meeting three out of four pathogenicity criteria, or potentially pathogenic, as defined in our study in 33 patients. They were judged as potentially pathogenic for clinical care and management with disease surveillance based on the specific gene and phenotypic presentation. Gene variants in collagen-related proteins were the most frequent with ZNF469 and ADAMTSL2 variants most often identified. Joint hypermobility was the most frequent clinical finding. Variants were found in 76% of patients who had distinct clinical features of a HCTD. The data were stratified to provide insight into frequency and types of variants, their classification, and clinical manifestations.

A patient with a novel pathogenic variant in COL5A1 exhibiting prominent vascular and cardiac features

The Ehlers-Danlos Syndromes (EDS) are a group of inherited connective tissue disorders with a worldwide prevalence of 1 in 2500 to 1 in 5000 births irrespective of sex or ethnicity. Fourteen subtypes of Ehlers-Danlos Syndrome (EDS) have been described, each with characteristic phenotypes and associated genes. Pathogenic variants in COL5A1 and COL5A2 cause the classical EDS subtypes. Pathogenic variants in COL3A1 cause vascular EDS. In this case report, we describe a patient with a phenotype resembling that of vascular EDS, caused by a novel pathogenic variant in COL5A1.

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.

Whole-exome sequencing facilitates the differential diagnosis of Ehlers-Danlos syndrome (EDS)

Ehlers-Danlos syndromes (EDSs) are a group of rare monogenic conditions with strong heterogeneity and can be caused by 20 genes associating with the essence of the extracellular matrix (ECM). This study enrolled three cases with various subtypes of EDS. Clinical evaluation and genetic testing with whole-exome sequencing (WES) were performed. The clinical manifestations of all three patients were thoroughly monitored; and three de novo diagnostic variants, namely COL5A1: NM_001278074.1: c.4609-2A>C, COL3A1: NM_000090.3: c.3554G>T(p.Gly1185Val), and COL1A1: NM_000088.3: c.545G>T(p.Gly182Val) were identified from them, respectively. The findings in this study expanded the mutation spectrum of EDS and strengthened the efficiency of WES in the differential diagnosis on disorders with overlapping phenotypes and various pathogenesis.

Gastric perforation leading to the diagnosis of classic Ehlers-Danlos syndrome: a case report

BACKGROUND

Ehlers-Danlos syndrome is a clinically and genetically heterogeneous group of heritable connective tissue disorders caused by a defect in collagen synthesis and structure. The vascular subtype (Ehlers-Danlos syndrome IV) is reported to be associated with a higher incidence of gastrointestinal perforations. The most reported site of perforation is the colon, followed by the small bowel. Perforation of the stomach is very rare, and there are no reported cases to date of classic types I and II.

CASE PRESENTATION

We present the case of a 14-year-old Saudi girl who visited our emergency department with abdominal pain and vomiting. Initially, she was diagnosed with gastroenteritis and discharged once her condition stabilized. After 48 hours, she developed severe abdominal pain with recurrent vomiting and peritonitis evident on clinical examination. Initial abdominal x-ray failed to show any free air; however, enhanced computed tomography revealed free air and contrast extravasation in the proximal gut. During exploratory laparotomy, a large perforation was found on the anterior wall of the stomach due to the underlying ischemia. The posterior wall had ischemic mucosa with an intact healthy serosa. A free-hand partial gastrectomy was performed to resect all ischemic parts of the stomach. Detailed examinations and laboratory workup were carried out after the surgery to figure out the possible underlying cause. The clinical findings during the physical examination supported marfanoid features. Marfan's syndrome and related disorders sequencing panel was requested, and Deoxyribonucleic acid (DNA) samples were sent. Given results were supporting the diagnosis of classical Ehlers-Danlos syndrome, the patient was labeled as a case of Ehlers-Danlos syndrome. During the postoperative period, she developed a wound infection that was managed successfully with vacuum-assisted closure dressing. She recovered well without gastrointestinal sequelae in the 4 years of follow-up.

CONCLUSIONS

Heritable systemic connective tissue diseases must be given serious consideration in young patients with unusual spontaneous perforation. Such patients might develop life-threatening conditions that require immediate intervention. Hence, correct and timely diagnosis is important to prepare for the anticipated complications.

Biomarkers for Ehlers-Danlos Syndromes: There Is a Role?

Ehlers-Danlos syndromes (EDS) are an inherited heterogeneous group of connective tissue disorders characterized by an abnormal collagen synthesis affecting skin, ligaments, joints, blood vessels, and other organs. It is one of the oldest known causes of bruising and bleeding, and it was described first by Hippocrates in 400 BC. In the last years, multiple gene variants involved in the pathogenesis of specific EDS subtypes have been identified; moreover, new clinical diagnostic criteria have been established. New classification models have also been studied in order to differentiate overlapping conditions. Moreover, EDS shares many characteristics with other similar disorders. Although distinguishing between these seemingly identical conditions is difficult, it is essential in ensuring proper patient care. Currently, there are many genetic and molecular studies underway to clarify the etiology of some variants of EDS. However, the genetic basis of the hypermobile type of EDS (hEDS) is still unknown. In this review, we focused on the study of two of the most common forms of EDS—classic and hypermobile—by trying to identify possible biomarkers that could be of great help to confirm patients’ diagnosis and their follow up.

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.

A novel mutation in COL3A1 associates to vascular Ehlers-Danlos syndrome with predominant musculoskeletal involvement

Background

Vascular Ehlers–Danlos syndrome (vEDS) is a heritable connective tissue disorder caused by defects in the type III collagen protein. It is generally considered the most severe form of Ehlers–Danlos syndrome (EDS) due to an increased risk of spontaneous artery or organ rupture. vEDS has an extremely heterogeneous presentation and muscle rupture is considered a minor diagnostic criterium.

Methods

A patient with a long history of inconclusive examinations and investigations was referred to our unit. The clinical picture was mainly characterized by muscle ruptures, whereas the cardiovascular involvement was limited to mitral regurgitation. We performed a panel analysis of genes associated with inheritable heart diseases using the TruSight Cardio kit (Illumina). A skin biopsy was then performed for functional studies to analyze the different forms of collagen molecules produced in vitro by cutaneous fibroblasts.

Results

The patient presented the novel variant c.3478A>G (p.Ile1160Val) in COL3A1 (NM_000090.3), whose pathogenicity was supported by biochemical analysis of type III collagen.

Conclusion

In this report, we describe a case of vEDS with predominant and severe musculoskeletal involvement. Our findings provide insight into genetic variants and clinical expression of vEDS, broadening the clinical scenario of the syndrome.

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.

Ehlers-Danlos syndrome-related genes and serum strontium, zinc, and lithium levels in generalized joint hypermobility: a case-control study

Aim of the study: Generalized joint hypermobility (GJH) is a common feature of almost all Ehlers-Danlos syndrome (EDS) types; however, its genetic basis remains unclear. Therefore, it is crucial to distinguish the genetic basis of GJH from other connective tissue disorders, including the different subtypes of EDS. The aim of this study was to determine the blood EDS-related gene expressions and serum element levels in GJH and reveal their predictive characteristics and correlations with the Beighton score. Materials and Methods: A total of 39 women aged 18-23 years with GJH and 38 age- and sex-matched controls were included in the study. Inductively coupled plasma mass spectrometry was used to analyze the serum levels of zinc (Zn), strontium (Sr), and lithium (Li). The relative expression levels of the EDS-related genes were determined using quantitative real-time polymerase chain reaction (PCR). Results: Our results showed that women with GJH possessed significantly lower Li and higher Zn and Sr levels than the controls. In addition, the gene expressions of TNXB and SLC39A13 were significantly higher, whereas those of COL1A1, COL1A2, COL5A1, FKBP14, and DSE were lower in the GJH group. Pearson correlation analyses revealed a strong negative correlation between the Beighton score and B4GALT7, FKBP14, COL1A1, and Li. However, a significant positive correlation was noted between the Beighton score and SLC39A13, TNXB, Zn, Sr, and B3GALT6. Conclusion: Our findings provide valuable basal levels for conducting gene function analysis of joint hypermobility-related connective tissue disorders.

Single-Cell RNA Sequencing and Quantitative Proteomics Analysis Elucidate Marker Genes and Molecular Mechanisms in Hypoplastic Left Heart Patients With Heart Failure

Objective

To probe markers and molecular mechanisms of the hypoplastic left heart (HLH) by single-cell RNA sequencing (scRNA-seq) and quantitative proteomics analysis.

Methods

Following data preprocessing, scRNA-seq data of pluripotent stem cell (iPSC)-derived cardiomyocytes from one HLH patient and one control were analyzed by the Seurat package in R. Cell clusters were characterized, which was followed by a pseudotime analysis. Markers in the pseudotime analysis were utilized for functional enrichment analysis. Quantitative proteomics analysis was based on peripheral blood samples from HLH patients without heart failure (HLH-NHF), HLH patients with heart failure (HLH-HF), and healthy controls. Hub genes were identified by the intersection of pseudotime markers and differentially expressed proteins (DE-proteins), which were validated in the GSE77798 dataset, RT-qPCR, and western blot.

Results

Cardiomyocytes derived from iPSCs were clustered into mesenchymal stem cells, myocardium, and fibroblast cells. Pseudotime analysis revealed their differentiation trajectory. Markers in the three pseudotime clusters were significantly associated with distinct biological processes and pathways. Finally, three hub genes (MMP2, B2M, and COL5A1) were identified, which were highly expressed in the left (LV) and right (RV) ventricles of HLH patients compared with controls. Furthermore, higher expression levels were detected in HLH patients with or without HF than in controls.

Conclusion

Our findings elucidate marker genes and molecular mechanisms of HLH, deepening the understanding of the pathogenesis of HLH.

Low penetrance COL5A1 variants in a young patient with intracranial aneurysm and very mild signs of Ehlers-Danlos syndrome

Spontaneous cervical artery dissection (CeAD) is a major cause of ischemic stroke in young adults, whose genetic susceptibility factors are still largely unknown. Nevertheless, subtle ultrastructural connective tissue alterations (especially in the collagen fibril morphology) are recognized in a large proportion of CeAD patients, in which recent genetic investigations reported an enrichment of variants in genes associated with known connective tissue disorders. In this regard, COL5A1 variants have been reported in a small subset of CeAD patients, with or without classical Ehlers-Danlos syndrome (cEDS) features. We investigated a 22-year-old patient with intracranial aneurysm and mild connective tissue manifestations reminiscent of EDS. Whole-exome sequencing identified two COL5A1 missense variants in trans configuration: NM_000093.5:c.[1588G>A];[4135C>T], NP_000084.3:p.[(Gly530Ser)];[(Pro1379Ser)]. Functional assays demonstrated a significant decrease of collagen α1(V) chain expression in both heterozygous parents compared to control cells, and an additive effect of these two variants in the proband. Interestingly, both parents manifested very subtle EDS signs, such as atrophic scars, recurrent bone fractures, colonic diverticulosis, varicose veins, and osteoarthritis. Our findings emphasize the involvement of COL5A1 in the predisposition to vascular phenotypes and provide novel insights on the c.1588G>A variant, whose functional significance has not been definitely established. In fact, it was previously reported as both "disease modifying", and as a biallelic causative mutation (with heterozygous individuals showing subtle clinical signs of cEDS). We speculated that the c.1588G>A variant might lead to overt phenotype in combination with additional genetic "hits" lowering the collagen α1(V) chain expression below a hypothetical disease threshold.

Arterial complications in classical Ehlers-Danlos syndrome: a case series

BACKGROUND

The Ehlers-Danlos syndromes (EDS) are a group of connective tissue disorders with several recognised types. Patients with a type of EDS have connective tissue abnormalities resulting in a varying degree of joint hypermobility, skin and vascular fragility and generalised tissue friability. Classical EDS (cEDS) typically occurs as a result of dominant pathogenic variants in COL5A1 or COL5A2. The cardinal features of cEDS are hyperextensible skin, atrophic scarring and joint hypermobility. Arterial complications are more characteristically a feature of vascular EDS although individual cases of arterial events in cEDS have been reported.

METHODS

A cohort of 154 patients with a clinical diagnosis of cEDS from the UK was analysed.

RESULTS

Seven patients (4.5%) with a diagnosis of cEDS (four pathogenic, one likely pathogenic and two variants of uncertain significance in COL5A1) who had experienced arterial complications were identified. Arterial complications mostly involved medium-sized vessels and also two abdominal aortic aneurysms. No unique clinical features were identified in this group of patients.

CONCLUSION

There is a possible increased risk of arterial complications in patients with cEDS, although not well-defined. Clinicians need to be aware of this possibility when presented with a patient with an arterial complication and features of cEDS. Long-term management in families with cEDS and a vascular complication should be individually tailored to the patient's history and their family's history of vascular events.

Characterization of the development of the mouse cochlear epithelium at the single cell level

Mammalian hearing requires the development of the organ of Corti, a sensory epithelium comprising unique cell types. The limited number of each of these cell types, combined with their close proximity, has prevented characterization of individual cell types and/or their developmental progression. To examine cochlear development more closely, we transcriptionally profile approximately 30,000 isolated mouse cochlear cells collected at four developmental time points. Here we report on the analysis of those cells including the identification of both known and unknown cell types. Trajectory analysis for OHCs indicates four phases of gene expression while fate mapping of progenitor cells suggests that OHCs and their surrounding supporting cells arise from a distinct (lateral) progenitor pool. Tgfβr1 is identified as being expressed in lateral progenitor cells and a Tgfβr1 antagonist inhibits OHC development. These results provide insights regarding cochlear development and demonstrate the potential value and application of this data set.

How the development of the cochlear epithelium is regulated is unclear. Here, the authors use single cell RNAseq analysis to provide insight into the transcriptional changes arising during development of the murine cochlear inner and outer hair cells.

Bone Disease in Patients with Ehlers-Danlos Syndromes

PURPOSE OF REVIEW

To summarize the bone findings, mainly bone mass and fracture risk, in Ehlers-Danlos syndromes (EDS).

RECENT FINDINGS

Low bone mineral density and fractures seem to be frequent in some of the rare EDS types (kyphoscoliotic, arthrochalasia, spondylodysplastic, and classic-like EDS). For the more prevalent hypermobile and classic EDS types, some case-control studies found mildly decreased bone mineral density, but it was not clear that fracture rates were increased. Nevertheless, abnormalities in vertebral shape seem to be common in classical and hypermobile EDS types. In a cohort of individuals with EDS followed since birth, no fractures were observed during infancy. Bone mineral density varies widely among the different types of EDS, and vertebral abnormalities seem to be common in classical and hypermobile EDS. It might be justified to perform spine radiographs and bone mineral density assessments in newly diagnosed EDS.

Absence of Collagen Flowers on Electron Microscopy and Identification of (Likely) Pathogenic COL5A1 Variants in Two Patients

Two probands are reported with pathogenic and likely pathogenic COL5A1 variants (frameshift and splice site) in whom no collagen flowers have been identified with transmission electron microscopy (TEM). One proband fulfils the clinical criteria for classical Ehlers-Danlos syndrome (cEDS) while the other does not and presents with a vascular complication. This case report highlights the significant intrafamilial variability within the cEDS phenotype and demonstrates that patients with pathogenic COL5A1 variants can have an absence of collagen flowers on TEM skin biopsy analysis. This has not been previously reported in the literature and is important when evaluating the significance of a TEM result in patients with clinically suspected cEDS and underscores the relevance of molecular analysis.

Biallelic B3GALT6 mutations cause spondylodysplastic Ehlers-Danlos syndrome

Proteoglycans are among the most abundant and structurally complex biomacromolecules and play critical roles in connective tissues. They are composed of a core protein onto which glycosaminoglycan (GAG) side chains are attached via a linker region. Biallelic mutations in B3GALT6, encoding one of the linker region glycosyltransferases, are known to cause either spondyloepimetaphyseal dysplasia (SEMD) or a severe pleiotropic form of Ehlers-Danlos syndromes (EDS). This study provides clinical, molecular and biochemical data on 12 patients with biallelic B3GALT6 mutations. Notably, all patients have features of both EDS and SEMD. In addition, some patients have severe and potential life-threatening complications such as aortic dilatation and aneurysm, cervical spine instability and respiratory insufficiency. Whole-exome sequencing, next generation panel sequencing and direct sequencing identified biallelic B3GALT6 mutations in all patients. We show that these mutations reduce the amount of β3GalT6 protein and lead to a complete loss of galactosyltransferase activity. In turn, this leads to deficient GAG synthesis, and ultrastructural abnormalities in collagen fibril organization. In conclusion, this study redefines the phenotype associated with B3GALT6 mutations on the basis of clinical, molecular and biochemical data in 12 patients, and provides an in-depth assessment of β3GalT6 activity and GAG synthesis to better understand this rare condition.

Inter-rater reliability of phenotypes and exploratory genotype-phenotype analysis in inherited hidradenitis suppurativa

BACKGROUND

Genotype-phenotype correlation measures the correlation between the presence of a physical trait with a group of similar mutations but is dependent on reliable phenotyping. It can provide information on disease pathogenesis, future disease progression, severity or activity. Such indicators would be valuable in hidradenitis suppurativa (HS).

OBJECTIVES

To assess inter-rater reliability (IRR) of HS clinical phenotypes and perform exploratory genotype-phenotype correlation in cases of HS with identified sequence variants.

METHODS

Linkage disequilibrium between variants was assessed. Genotype-phenotype correlations were explored using Spearman correlation coefficients. IRR was calculated using Cohen's κ. Correlation between phenotype classifications was assessed using the χ² statistic.

RESULTS

Forty-three sequence variants with clinical information were identified. Clinical phenotypes were classified as LC2 (n = 29; 67%), scarring folliculitis (n = 18; 42%), atypical (n = 38; 88%) and nodular (n = 26; 60%). LC1 phenotype was associated with regular (χ² = 41·289, P < 0·001) and typical (χ² = 29·013, P < 0·001) phenotypes. Cohen's κ was highest for van der Zee and Jemec (0·815), followed by Martorell-Calatayud et al. (0·813), Naasan and Affleck (0·774) and Canoui-Poitrine et al. (0·435) classifications. High linkage disequilibrium was seen between variants of Han Chinese pedigrees. No significant genotype-phenotype correlations were identified.

CONCLUSIONS

These findings may be influenced by selection, publication bias and the assumption that HS is a monogenic disorder. The poor IRR of existing phenotype measures suggests limited utility of existing measures. Further investigations into the correlation of clinical phenotypes with inflammatory biomarkers may aid in prognostic efforts for this disease. What's already known about this topic? Genotype-phenotype correlation can provide information regarding disease pathogenesis and predictions for future disease progression, severity or activity. The identification of such indicators in hidradenitis suppurativa (HS) would be valuable for patients and clinicians alike, given the lack of biomarkers or clinical predictors of disease. What does this study add? Sixty-five sequence variants across 20 separate genes were identified. There was no significant correlation between phenotype classification in four separate classification schema and gene, mutation type or impact on Notch signalling. Utility of current phenotype measurements are limited. The lack of genotype-phenotype correlation in HS is suggestive that the underlying assumption of inherited HS as a monogenic disorder may need revision.

Atypical COL3A1 variants (glutamic acid to lysine) cause vascular Ehlers-Danlos syndrome with a consistent phenotype of tissue fragility and skin hyperextensibility

PURPOSE

The Ehlers-Danlos syndromes (EDS) are a group of rare inherited connective tissue disorders. Vascular EDS (vEDS) is caused by pathogenic variants in COL3A1, most frequently glycine substitutions. We describe the phenotype of the largest series of vEDS patients with glutamic acid to lysine substitutions (Glu>Lys) in COL3A1, which were all previously considered to be variants of unknown significance.

METHODS

Clinical and molecular data for seven families with three different Glu>Lys substitutions in COL3A1 were analyzed.

RESULTS

These Glu>Lys variants were reclassified from variants of unknown significance to either pathogenic or likely pathogenic in accordance with American College of Medical Genetics and Genomics guidelines. All individuals with these atypical variants exhibited skin hyperextensibility as seen in individuals with classical EDS and classical-like EDS and evidence of tissue fragility as seen in individuals with vEDS.

CONCLUSION

The clinical data demonstrate the overlap between the different EDS subtypes and underline the importance of next-generation sequencing gene panel analysis. The three different Glu>Lys variants point toward a new variant type in COL3A1 causative of vEDS, which has consistent clinical features. This is important knowledge for COL3A1 variant interpretation. Further follow-up data are required to establish the severity of tissue fragility complications compared with patients with other recognized molecular causes of vEDS.

Accuracy of Clinical Diagnostic Criteria for Patients With Vascular Ehlers-Danlos Syndrome in a Tertiary Referral Centre

Background:

Vascular Ehlers-Danlos syndrome is a rare inherited connective tissue disease secondary to mutations within the COL3A1 gene. The diagnosis of vascular Ehlers-Danlos syndrome is challenging, and patient selection for genetic testing relies on diagnostic criteria, which have never been evaluated.

Methods:

All patients seen at a dedicated tertiary referral center for a suspicion of vascular Ehlers-Danlos syndrome between January 2001 and March 2016 were retrospectively included in a diagnostic accuracy study. Major and minor diagnostic criteria of the Villefranche classification were tested for sensitivity, specificity, positive and negative predictive values, according to results of genetic testing.

Results:

N=519 patients were eligible for analysis dividing into n=384 probands and n=135 relatives. A pathogenic COL3A1 variant was identified in n=165 (31.8%) patients. The Villefranche criteria were met for n=248 patients with a sensitivity of 79% (95% CI, 0.72–0.85) and a negative predictive value of 87% (95% CI, 0.83–0.91). Diagnostic accuracy was highest for symptomatic probands (sensitivity 92%; negative predictive value 95%) with limited specificity (60%). Probands ≤25 years had the worst diagnostic performance. The revised diagnostic Criteria (2017) were less accurate than the Villefranche classification (overall diagnostic odds-ratio, 4.17 versus 7.8; probands diagnostic odds-ratio, 4.04 versus 18.1; and probands ≤25 years diagnostic odds-ratio, 2.36 versus 5.1) mainly due to a lack of sensitivity.

Conclusions:

The Villefranche criteria provide accurate detection of symptomatic probands in specialized practice but have limited specificity. The revised diagnostic criteria for vascular Ehlers-Danlos syndrome have increased specificity, but its overall performance is poorer. The early clinical diagnosis of probands without family history is not addressed by both diagnostic classifications.

Genome damage in children with classical Ehlers-Danlos syndrome - An in vivo and in vitro study

Ehlers-Danlos syndrome (EDS) is a heritable connective tissue disorder characterized by skin hyperextensibility, abnormal wound healing, and joint hypermobility with prevalence 1:20 000. Its incidence is probably underestimated due to unknown number of subjects having mild symptoms who may have never been diagnosed through entire life time. Classical EDS is characterized by pathogenic variants of genes encoding type V collagen. The biological effects and health risks of patients with EDS exposure to low doses of ionizing radiation is poorly understood. The aim of this study was to investigate biological effect of low doses of ionizing radiation in children with EDS. Background values of chromosome aberrations in children suffering from classical EDS were determined and compared with control subjects. The in vitro experiment was performed by γ-irradiation of blood lymphocytes from EDS patients and healthy subjects at low doses (0.1, 0.2 and 0.3 Gy). Results show a significant increase level of spontaneous and radiation-induced chromosomal aberrations in children suffering from EDS in comparison with the control subjects (p < 0.05). In conclusion, children with EDS express higher background chromosome aberration frequency and increased radiosensitivity. These findings suggest specific susceptibility of EDS patients and importance of future investigation on risks of diagnostics and therapy which include radiation and genotoxic agents.

Application of immunotherapy for neurological manifestations in hypermobile Ehlers-Danlos syndrome

Ehlers–Danlos syndrome (EDS) is a heterogeneous heritable connective tissue disorder with various neurological manifestations, including chronic pain. The neurological manifestations in EDS are often regarded as being caused by the associated musculoskeletal disorders or polyneuropathy. Here, we present two patients with hypermobile EDS (hEDS), presenting with relapsing central nervous system (CNS) manifestations. Although the two patients showed relapsing signs of CNS manifestations like multiple sclerosis (MS) or neuromyelitis optica spectrum disorder (NMOSD), they were unique in that they had widespread opioid-dependent chronic pain, which is not consistent with the symptoms of MS/NMOSD. Unexpectedly, the serious pain of unknown origin was remarkably mitigated by plasmapheresis, and magnetic resonance imaging (MRI) examinations conducted for one of the patients were negative. Collectively, we speculate that hEDS may be more susceptible to ‘normal-appearing imaging, neuroimmunologically justified, autoimmune-mediated encephalomyelitis (NINJA).’ Analysis of the presented cases and an additional three patients with EDS with chronic pain indicates that treatable immune-mediated mechanisms deserve considerations for neurological symptoms observed in hEDS.

Targeted genetic analysis in a large cohort of familial and sporadic cases of aneurysm or dissection of the thoracic aorta

Purpose

Thoracic aortic aneurysm/aortic dissection (TAAD) is a disorder with highly variable age of onset and phenotype. We sought to determine the prevalence of pathogenic variants in TAAD-associated genes in a mixed cohort of sporadic and familial TAAD patients and identify relevant genotype-phenotype relationships.

Methods

We used a targeted PCR and next generation sequencing-based panel for genetic analysis of 15 TAAD associated genes in 1025 unrelated TAAD cases.

Results

We identified 49 pathogenic or likely pathogenic (P/LP) variants in 47 cases (4.9% of those successfully sequenced). Almost half of the variants were in non-syndromic cases with no known family history of aortic disease. Twenty-five variants were within FBN1 and two patients were found to harbour two P/LP variants. Presence of a related syndrome, younger age at presentation, family history of aortic disease and involvement of the ascending aorta increased the risk of carrying a P/LP variant.

Conclusions

Given the poor prognosis of TAAD that is undiagnosed prior to acute rupture or dissection, genetic analysis of both familial and sporadic cases of TAAD will lead to new diagnoses, more informed management and possibly reduced mortality through earlier, preclinical diagnosis in genetically determined cases and their family members.

The 2017 international classification of the Ehlers-Danlos syndromes

The Ehlers-Danlos syndromes (EDS) are a clinically and genetically heterogeneous group of heritable connective tissue disorders (HCTDs) characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. Over the past two decades, the Villefranche Nosology, which delineated six subtypes, has been widely used as the standard for clinical diagnosis of EDS. For most of these subtypes, mutations had been identified in collagen-encoding genes, or in genes encoding collagen-modifying enzymes. Since its publication in 1998, a whole spectrum of novel EDS subtypes has been described, and mutations have been identified in an array of novel genes. The International EDS Consortium proposes a revised EDS classification, which recognizes 13 subtypes. For each of the subtypes, we propose a set of clinical criteria that are suggestive for the diagnosis. However, in view of the vast genetic heterogeneity and phenotypic variability of the EDS subtypes, and the clinical overlap between EDS subtypes, but also with other HCTDs, the definite diagnosis of all EDS subtypes, except for the hypermobile type, relies on molecular confirmation with identification of (a) causative genetic variant(s). We also revised the clinical criteria for hypermobile EDS in order to allow for a better distinction from other joint hypermobility disorders. To satisfy research needs, we also propose a pathogenetic scheme, that regroups EDS subtypes for which the causative proteins function within the same pathway. We hope that the revised International EDS Classification will serve as a new standard for the diagnosis of EDS and will provide a framework for future research purposes. © 2017 Wiley Periodicals, Inc.

Review of Clinical Next-Generation Sequencing

CONTEXT

- Next-generation sequencing (NGS) is a technology being used by many laboratories to test for inherited disorders and tumor mutations. This technology is new for many practicing pathologists, who may not be familiar with the uses, methodology, and limitations of NGS.

OBJECTIVE

- To familiarize pathologists with several aspects of NGS, including current and expanding uses; methodology including wet bench aspects, bioinformatics, and interpretation; validation and proficiency; limitations; and issues related to the integration of NGS data into patient care.

DATA SOURCES

- The review is based on peer-reviewed literature and personal experience using NGS in a clinical setting at a major academic center.

CONCLUSIONS

- The clinical applications of NGS will increase as the technology, bioinformatics, and resources evolve to address the limitations and improve quality of results. The challenge for clinical laboratories is to ensure testing is clinically relevant, cost-effective, and can be integrated into clinical care.

Multiple fractures in infants who have Ehlers-Danlos/hypermobility syndrome and or vitamin D deficiency: A case series of 72 infants whose parents were accused of child abuse and neglect

Objective: To increase the level of awareness that Ehlers-Danlos/hypermobility syndrome (EDS) and vitamin D deficiency are associated with infantile fragility fractures and radiologic features that may be mistakenly reported to be caused by non-accidental trauma due to Child Abuse and Neglect (CAN).

Patients and Methods: We constructed a case series, the largest to date, of infants with EDS who were vitamin D sufficient, insufficient and deficient and infants without EDS but with documented vitamin D deficiency and radiologic evidence of rickets who presented with multiple fractures originally diagnosed as being non-accidental and caused by child abuse. These infants were referred to the outpatient Bone Health Care Clinic at Boston University Medical Campus over a 6-year (2010–2015) period. We also present 6 index cases in which the court concluded that there was no convincing evidence of child abuse and the infants were returned to their parents. Institutional Review Board (IRB) approval was obtained.

Results: We present 72 cases of infants with multiple fractures diagnosed to be caused by non-accidental trauma. All infants were younger than one year of age. Among them, 93%(67) had clinical evidence of EDS and/or a family history with a confirmed clinical diagnosis of at least one parent having EDS and the other 7%(5) without evidence of EDS had vitamin D deficiency/infantile rickets. Three of the EDS infants were diagnosed as osteogenesis imperfecta (OI)/EDS overlap syndrome. The most common fractures noted at diagnosis were ribs and extremity fractures (including classic metaphyseal lesions). Serum levels of 25-hydroxyvitamin D [25(OH)D] were reported in 48 infants (18.0 ± 8.5 ng/ml) and in 30 mothers (21.3 ± 11.7 ng/ml). Sixty-three percent (27) of the EDS infants who had their serum 25(OH)D measured were vitamin D deficient 25(OH)D<20 ng/ml and 5 were vitamin D sufficient 25(OH)D>30 ng/ml. The mean serum level for infants with vitamin D deficiency/rickets was (10.2 ± 3.0 ng/ml)

Conclusion: EDS, OI/EDS and vitamin D deficiency/infantile rickets are associated with fragility fractures in infants that can be misinterpreted as caused by non-accidental trauma due to child abuse.

Hypermobile Ehlers-Danlos syndrome (a.k.a. Ehlers-Danlos syndrome Type III and Ehlers-Danlos syndrome hypermobility type): Clinical description and natural history

The hypermobile type of Ehlers-Danlos syndrome (hEDS) is likely the most common hereditary disorder of connective tissue. It has been described largely in those with musculoskeletal complaints including joint hypermobility, joint subluxations/dislocations, as well as skin and soft tissue manifestations. Many patients report activity-related pain and some go on to have daily pain. Two undifferentiated syndromes have been used to describe these manifestations-joint hypermobility syndrome and hEDS. Both are clinical diagnoses in the absence of other causation. Current medical literature further complicates differentiation and describes multiple associated symptoms and disorders. The current EDS nosology combines these two entities into the hypermobile type of EDS. Herein, we review and summarize the literature as a better clinical description of this type of connective tissue disorder. © 2017 Wiley Periodicals, Inc.

A novel missense mutation of COL5A2 in a patient with Ehlers-Danlos syndrome

Ehlers–Danlos syndrome (EDS) is a group of inherited connective tissue disorders characterized by hyperextensible skin, joint hypermobility and soft tissue fragility. For molecular diagnosis, targeted exome sequencing was performed on a 9-year-old male patient who was clinically suspected to have EDS. The patient presented with progressive kyphoscoliosis, joint hypermobility and hyperextensible skin without scars. Ultimately, classical EDS was diagnosed by identifying a novel, mono-allelic mutation in COL5A2 [NM_000393.3(COL5A2_v001):c.682G>A, p.Gly228Arg].