Mutation in TNXB gene causes moderate to severe Ehlers-Danlos syndrome

Treatments related to temporomandibular disorders among patients with prevalent types of Ehlers-Danlos syndrome in Sweden

The aim of this study was to assess the received TMD treatment modalities and the perceived outcome among the frequent types of EDS. A digital questionnaire was sent to the member of the National Swedish EDS Association during January-March 2022. The subsamples of hypermobile and classical EDS were constructed. Almost 90% reported TMD symptoms. Bite splint therapy, counselling, jaw training and occlusal adjustment were reported as the most common treatments with no statistically significant difference in terms of good effect between the two subsamples. Hypermobile and classical EDS might consider as an entity with regards to TMD.

The role of gene encoding collagen secretion protein (SERPINH1) in the pathogenesis of a hypermobile type of Ehlers-Danlos syndrome

Introduction

Hypermobile (hEDS) Ehlers-Danlos syndrome (EDS) is a non-inflammatory, autosomal dominant connective tissue disorder. hEDS, unlike other types of EDS, has no known genetic aetiology, so diagnosis is conducted based on a person's medical history, a physical examination, and exclusion of other types of EDS after genetic tests.

Aim

The present study was a sequencing analysis of the SERPINH1 gene and the evaluation of the potential impact of variants of this gene on their role in the aetiology of the hypermobile type of EDS.

Material and methods

The study group included 100 hEDS patients of Polish origin. The SERPINH1 gene analysis was performed on genomic DNA (gDNA). In all patients, other types of EDS or other connective tissue disorders were excluded by testing them with NGS technology.

Results

Among 100 tested patients, 4 different types of missense variants (heterozygote) were detected. All SERPINH1 alterations were classified as benign according to ACMG guidelines.

Conclusions

Mutations in the SERPINH1 gene have been described in a rare type of OI but have never been analysed in hypermobile Ehlers-Danlos syndrome. In our investigation among 100 hEDS patients, we did not identify pathogenic or likely pathogenic variants. Though only benign variants were detected, which play no role in the pathogenesis of hEDS, we should take into account mechanisms other than gene structure alterations, which may have an impact on collagen and other ECM protein transport.

Clinical genetics evaluation and testing of connective tissue disorders: a cross-sectional study

BACKGROUND

Heritable connective tissue disorders (HCTDs) consist of heterogeneous syndromes. The diagnosis of HCTDs is aided by genomic biotechnologies (e.g., next-generation sequencing panels) facilitating the discovery of novel variants causing disease.

METHODS

Detailed clinical exam data and CLIA-approved genetic testing results from next generation sequencing of 74 genes known to play a role in HCTDs were manually reviewed and analyzed in one hundred consecutive, unrelated patients with phenotypic features indicative of a HCTD referred over a 3.5-year period (2016-2020) to a specialized academic genetics clinic. The prevalence of symptoms was evaluated in the context of genetic variants. We also determined if symptoms among different organ systems were related and performed latent class analysis to identify distinct groups of patients based on symptomatology.

RESULTS

In the cohort of 100 consecutive, unrelated individuals there were four pathogenic, six likely pathogenic and 35 classified potentially pathogenic variants of unknown clinical significance. Patients with potentially pathogenic variants exhibited similar symptom profiles when compared to patients with pathogenic/likely pathogenic variants in the same genes. Although results did not meet a multiple testing corrected threshold, patients with connective tissue symptoms had suggestive evidence of increased odds of having skin (odds ratio 2.18, 95% confidence interval 1.12 to 4.24) and eye symptoms (odds ratio 1.89, 95% confidence interval 0.98 to 3.66) requiring further studies. The best performing latent class analysis results were identified when dividing the dataset into three distinct groups based on age, gender and presence or absence of symptoms in the skeletal, connective tissue, nervous, gastrointestinal and cardiovascular systems. These distinct classes of patients included individuals with: (1) minimal skeletal symptoms, (2) more skeletal but fewer connective tissue, nervous or gastrointestinal symptoms and (3) more nervous system symptoms.

CONCLUSIONS

We used novel approaches to characterize phenotype-genotype relationships, including pinpointing potentially pathogenic variants, and detecting unique symptom profiles in patients with features of HCTDs. This study may guide future diagnosis and disease/organ system monitoring with continued improvement and surveillance by clinicians for patients and their families.

Rare neurological manifestations in a Saudi Arabian patient with Ehlers-Danlos syndrome and a novel homozygous variant in the TNXB gene

We report a 38-year-old Saudi male with Ehlers-Danlos Syndrome (EDS). The patient presented with rare and unusual neurological manifestations, including but not limited to ophthalmoplegia and myopathic pattern on his electromyography. In addition to hand weakness, there was skin hyperextensibility, joint hyperflexibility, and frontal baldness. Next-generation sequencing was performed on target exon sequences, using whole exome sequencing and Burrows-Wheeler Aligner for alignment/base calling. Genome Analysis Toolkit and reference genome Homo sapiens (UCSC hg19) were used for sequence processing and analysis. Variant classification was done according to standard international recommendations. A novel homozygous variant, NM_019105.6: c.8488C>T p.(Gln2830*), was detected in the TNXB gene. This variant is not reported in the literature nor dbSNP or gnomAD databases. Additionally, this variant is predicted to create a premature stop codon and produce a truncated protein or nonsense-mediated mRNA decay. Hence, it is classified as a likely pathogenic variant. The same point variant was found in a heterozygous state in the patient's father and sister. Both presented with milder symptoms associated with Ehlers-Danlos syndromes and heritable connective tissue disorders. Therefore, the patient was diagnosed as a tenascin-X (TNX) deficient type of EDS known as classical-like Ehlers-Danlos syndrome. TNX deficient patients may present with clinical and electrophysiological manifestations that are unusual in EDS like frontal baldness, ophthalmoplegia, and myotonia, which mimic myotonic dystrophy type I. Clinicians should be aware of the potential overlap of symptoms among these two diseases to ensure correct diagnosis is made.

Hypermobile Disorders and Their Effects on the Hip Joint

Hypermobility, or joint hyperlaxity, can result from inherited connective tissue disorders or from micro- or macrotrauma to a joint. The supraphysiologic motion of the hip joint results in capsuloligamentous damage, and these patients have a propensity to develop femoroacetabular impingement syndrome (FAIS) and labral injury. In this review, the recent literature evaluating the definitions, history, incidence, genetics, and histology of hypermobile disorders is investigated. We then review the clinical evaluation, natural history, and resulting instability for patients presenting with a hypermobile hip. Lastly, treatment options and outcomes will be highlighted.

Hypermobile Ehlers-Danlos syndromes: Complex phenotypes, challenging diagnoses, and poorly understood causes

The Ehlers-Danlos syndromes (EDS) are a group of heritable, connective tissue disorders characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. There is phenotypic and genetic variation among the 13 subtypes. The initial genetic findings on EDS were related to alterations in fibrillar collagen, but the elucidation of the molecular basis of many of the subtypes revealed several genes not involved in collagen biosynthesis or structure. However, the genetic basis of the hypermobile type of EDS (hEDS) is still unknown. hEDS is the most common type of EDS and involves generalized joint hypermobility, musculoskeletal manifestations, and mild skin involvement along with the presence of several comorbid conditions. Variability in the spectrum and severity of symptoms and progression of patient phenotype likely depend on age, gender, lifestyle, and expression domains of the EDS genes during development and postnatal life. In this review, we summarize the current molecular, genetic, epidemiologic, and pathogenetic findings related to EDS with a focus on the hypermobile type.

Classic Ehlers-Danlos syndrome and cardiac transplantation - Is there a connection?

Ehlers-Danlos syndrome (EDS) is a heterogeneous group of connective tissue disorders comprised of several types. Classic EDS is an autosomal dominant disorder with stretchable skin, delayed wound healing with poor scarring, joint hypermobility with subluxations or dislocations, easy bruisability, hernias, aneurysms and cardiac abnormalities. Advances in genomics technology using next-generation sequencing has led to the discovery of causative genes for connective tissue disorders, hereditary cardiomyopathies and cardiovascular diseases including several genes for connective tissue disorders. A 55 year-old male exhibited thin stretchable skin, atrophic scars, easy bruising, joint pain and dislocations requiring multiple knee surgeries and a Beighton hyperflexibility score of 6 out of 7. He was found to have a heterozygous missense COL5A1 gene variant involving exon 3 at nucleotide c:305T>A with an amino acid position change at p.lle102Asn consistent with classic EDS. He had a heart transplant at 43 years of age due to cardiac failure of unknown cause. This patient with classic EDS is brought to medical attention and should be of interest to cardiologists, heart transplant specialists and surgeons, particularly in individuals with unexplained cardiac failure and then diagnosed prior to surgical intervention to avoid poor wound healing, scarring and other tissue involvement (e.g., vascular anomalies, blood pressure instability, aneurysms) as components of EDS.

The Prevalence of the Chimeric TNXA/TNXB Gene and Clinical Symptoms of Ehlers-Danlos Syndrome with 21-Hydroxylase Deficiency

PURPOSE

Defects in both CYP21A2 and TNXB genes can cause congenital adrenal hyperplasia combined with hypermobility-type Ehlers-Danlos syndrome (EDS), which has recently been named CAH-X syndrome. The purpose of this study is to assess the prevalence of the chimeric TNXA/TNXB gene and clinical symptoms in a Chinese cohort with 21-hydroxylase deficiency (21-OHD).

METHODS

A total of 424 patients with 21-OHD who were genetically diagnosed were recruited for this study. Multiplex ligation-dependent probe amplification and sequencing were used to identify the CAH-X genotype. Clinical features of joints, skin, and other systems were evaluated in 125 patients.

RESULTS

Ninety-four of the 424 patients had a deletion on at least 1 allele of CYP21A2 and 59 of them harbored the heterozygotic TNXA/TNXB chimera. Frequencies of CAH-X CH-1, CH-2, and CH-3 were 8.2%, 3.1%, and 2.6%, respectively. The incidences of clinical features of EDS were 71.0% and 26.6% in patients with the chimeric TNXA/TNXB genes or without (P < .001). There were statistically significant differences in manifestations among articular (P < .001 in generalized hypermobility) and dermatologic features (P < .001 in hyperextensible skin, P = .015 in velvety skin and P = .033 in poor wound healing). The prevalence of generalized hypermobility was more common in CAH-X CH-2 or CH-3 than CH-1 patients (60% vs 20%, P = .028).

CONCLUSIONS

In summary, about 14% of patients with 21-OHD may have chimeric TNXA/TNXB gene mutations in our study and most of them showed EDS-related clinical symptoms. The correlation between CAH-X genotypes and clinical features in connective tissue, like joint or skin, needs to be further investigated.

Novel TNXB Variants in Two Italian Patients with Classical-Like Ehlers-Danlos Syndrome

TNXB-related classical-like Ehlers-Danlos syndrome (TNXB-clEDS) is an ultrarare type of Ehlers-Danlos syndrome due to biallelic null variants in TNXB, encoding tenascin-X. Less than 30 individuals have been reported to date, mostly of Dutch origin and showing a phenotype resembling classical Ehlers-Danlos syndrome without atrophic scarring. TNXB-clEDS is likely underdiagnosed due to the complex structure of the TNXB locus, a fact that complicates diagnostic molecular testing. Here, we report two unrelated Italian women with TNXB-clEDS due to compound heterozygosity for null alleles in TNXB. Both presented soft and hyperextensible skin, generalized joint hypermobility and related musculoskeletal complications, and chronic constipation. In addition, individual 1 showed progressive finger contractures and shortened metatarsals, while individual 2 manifested recurrent subconjunctival hemorrhages and an event of spontaneous rupture of the brachial vein. Molecular testing found the two previously unreported c.8278C > T p.(Gln2760*) and the c.(2358 + 1_2359 − 1)_(2779 + 1_2780 − 1)del variants in Individual 1, and the novel c.1150dupG p.(Glu384Glyfs*57) and the recurrent c.11435_11524+30del variants in Individual 2. mRNA analysis confirmed that the c.(2358 + 1_2359 − 1)_(2779 + 1_2780 − 1)del variant causes a frameshift leading to a predicted truncated protein [p.(Thr787Glyfs*40)]. This study refines the phenotype recently delineated in association with biallelic null alleles in TNXB, and adds three novel variants to its mutational repertoire. Unusual digital anomalies seem confirmed as possibly peculiar of TNXB-clEDS, while vascular fragility could be more than a chance association also in this Ehlers-Danlos syndrome type.

Whole Blood Targeted Bisulfite Sequencing and Differential Methylation in the C6ORF10 Gene of Patients with Rheumatoid Arthritis

Objective.

Polymorphisms in human major histocompatibility complex (MHC) are the strongest genetic associations with rheumatoid arthritis (RA). Epigenome-wide methylation studies suggest DNA methylation changes within MHC may contribute to disease susceptibility. We profiled MHC-specific methylated CpG (5′–C–phosphate–G–3′) in autoantibody-positive patients with RA and matched unaffected anticitrullinated protein antibodies–negative first-degree relatives (ACPA−/FDR) from an indigenous North American (INA) population that is known to have prevalent RA.

Methods.

DNA was isolated from whole blood and targeted bisulfite sequencing was used to profile methylated CpG in patients with RA and ACPA−/FDR. Differentially methylated CpG loci (DML) were mapped and gene annotated. Ingenuity pathway analysis (IPA) was used for curating biomolecular networks of mapped genes. Transcript abundance was determined by quantitative (q)PCR.

Results.

We identified 74 uniquely methylated CpG sites within the MHC region that were differentially methylated in patients with RA (p < 0.05), compared to ACPA−/FDR. Of these, 32 DML were located on 22 genes. IPA showed these genes are involved in regulating the nuclear factor–κB complex and processes involved in antigen presentation, and immune cell crosstalk in autoimmunity. Pearson correlation analysis demonstrated a negative association between differentially methylated CpG in the C6ORF10 gene and risk factors associated with RA. Analysis by qPCR confirmed differential abundance of C6ORF10, TNXB, and HCG18 mRNA in patients with RA compared to ACPA−/FDR.

Conclusion.

Our results confirm the presence of differential methylation at specific gene loci within the MHC region of INA patients with RA. These epigenetic signatures may precede disease onset, or alternatively, may be a result of developing RA.

Ehlers-Danlos syndrome and other heritable connective tissue disorders that impact pregnancies can be detected using next-generation DNA sequencing

Ehlers-Danlos syndromes (EDS) are a genetically heterogeneous group of inherited connective tissue disorders classified into six major types with a variable collection of findings and different inheritance patterns. Although complications occur in about one-half of pregnancies in women with EDS, the majority can have a good outcome if managed appropriately. Classic EDS is characterized by joint hypermobility, loose skin with poor healing and easy bruising, musculoskeletal problems with chronic pain and at risk for pre-term delivery. In addition, the vascular form of EDS can have cardiac anomalies, aneurysms, gastrointestinal perforation and uterine rupture during pregnancy. Due to overlapping features among the connective tissue disorders, it is difficult to categorize the disorder into specific types without detailed genetic testing which is now available through advanced genomic technology using next-generation DNA sequencing, searching genomic databases and bioinformatics approach. Therefore, obstetrical complications are variable but relate to specific connective tissue disorders requiring an exact diagnosis. There are several dozen genes causing connective tissue disorders that are currently available for testing using next-generation sequencing and bioinformatics to provide pertinent care, treatment and surveillance of the affected pregnant woman but also for her at-risk fetus related to the specific heritable condition.

Compound heterozygosity for TNXB genetic variants in a mixed-breed dog with Ehlers-Danlos syndrome

The Ehlers-Danlos syndromes (EDSs) are a heterogeneous group of inherited connective tissue disorders characterized by skin hyperextensibility, joint hypermobility and tissue fragility. Inherited disorders similar to human EDS have been reported in different mammalian species. In the present study, we investigated a female mixed-breed dog with clinical signs of EDS. Whole-genome sequencing of the affected dog revealed two missense variants in the TNXB gene, encoding the extracellular matrix protein tenascin XB. In humans, TNXB genetic variants cause classical-like EDS or the milder hypermobile EDS. The affected dog was heterozygous at both identified variants. Each variant allele was transmitted from one of the case's parents, consistent with compound heterozygosity. Although one of the variant alleles, XM_003431680.3:c.2012G>A, p.(Ser671Asn), was private to the family of the affected dog and absent from whole-genome sequencing data of 599 control dogs, the second variant allele, XM_003431680.3:c.2900G>A, p.(Gly967Asp), is present at a low frequency in the Chihuahua and Poodle population. Given that TNXB is a functional candidate gene for EDS, we suggest that compound heterozygosity for the identified TNXB variants may have caused the EDS-like phenotype in the affected dog. Chihuahuas and Poodles should be monitored for EDS cases, which might confirm the hypothesized pathogenic effect of the segregating TNXB variant.

An acquired or heritable connective tissue disorder? A review of hypermobile Ehlers Danlos Syndrome

Hypermobile Ehlers Danlos Syndrome (hEDS) is a multifaceted disorder that is difficult to diagnose and manage primarily due to the unknown causes. Research on hEDS continues to evolve but tangible progress will be realized when the growing body of evidence compliments clinical practice. This critical review of the literature aims to stimulate lateral thinking about the pathogenesis, diagnosis and management of hEDS. The current international classification of Ehlers Danlos Syndrome introduced stricter diagnostic criteria for hEDS, which bore a blanket category (hypermobility spectrum disorders) for conditions presenting with symptomatic joint hypermobility, but do not match the hEDS diagnostic criteria. One would argue hEDS is another all-encompassing classification for heritable connective tissue disorders and or acquired musculoskeletal conditions without a definitive molecular basis. As scientific research progresses to accommodate validated and or annulled hypotheses, the plethora of unknowns in hEDS continue to challenge healthcare outcomes and care experiences.

Classic Ehlers-Danlos Syndrome in a Son and Father with a Heart Transplant Performed in the Father

We report a 13-year-old male patient with severe orthopedic problems including features of a connective tissue disorder and a heterozygous c.305T > A variant found within exon 3 of the autosomal dominant collagen ( COL5A1 ) gene causing the classic Ehlers-Danlos syndrome. This variant has not been reported previously and identified as having an unknown clinical significance but classified as trending damaging per in silico prediction with high conservation among species. Our patient's father had the same gene variant and similar features of stretchable skin, easy bruising, and multiple joint dislocations. The father had unexplained heart failure requiring cardiac transplantation at 43 years of age.

Vascular phenotypes in nonvascular subtypes of the Ehlers-Danlos syndrome: a systematic review

Purpose

Within the spectrum of the Ehlers-Danlos syndromes (EDS), vascular complications are usually associated with the vascular subtype of EDS. Vascular complications are also observed in other EDS subtypes, but the reports are anecdotal and the information is dispersed. To better document the nature of vascular complications among “nonvascular” EDS subtypes, we performed a systematic review.

Methods

We queried three databases for English-language studies from inception until May 2017, documenting both phenotypes and genotypes of patients with nonvascular EDS subtypes. The outcome included the number and nature of vascular complications.

Results

A total of 112 papers were included and data were collected from 467 patients, of whom 77 presented with a vascular phenotype. Severe complications included mainly hematomas (53%), frequently reported in musculocontractural and classical-like EDS; intracranial hemorrhages (18%), with a high risk in dermatosparaxis EDS; and arterial dissections (16%), frequently reported in kyphoscoliotic and classical EDS. Other, more minor, vascular complications were reported in cardiac-valvular, arthrochalasia, spondylodysplastic, and periodontal EDS.

Conclusion

Potentially life-threatening vascular complications are a rare but important finding in several nonvascular EDS subtypes, highlighting a need for more systematic documentation. This review will help familiarize clinicians with the spectrum of vascular complications in EDS and guide follow-up and management.