Arthrogryposis as a Syndrome: Gene Ontology Analysis

Features of Congenital Arthrogryposis Due to Abnormalities in Collagen Homeostasis, a Scoping Review

Congenital arthrogryposis (CA) refers to the presence of multiple contractures at birth. It is a feature of several inherited syndromes, notable amongst them are disorders of collagen formation. This review aims to characterize disorders that directly or indirectly impact collagen structure and function leading to CA in search for common phenotypic or pathophysiological features, possible genotype-phenotype correlation, and potential novel treatment approaches based on a better understanding of the underlying pathomechanism. Nine genes, corresponding to five clinical phenotypes, were identified after a literature search. The most notable trend was the extreme phenotype variability. Clinical features across all syndromes ranged from subtle with minimal congenital contractures, to severe with multiple congenital contractures and extra-articular features including skin, respiratory, or other manifestations. Five of the identified genes were involved in the function of the Lysyl Hydroxylase 2 or 3 enzymes, which enable the hydroxylation and/or glycosylation of lysyl residues to allow the formation of the collagen superstructure. Whilst current treatment approaches are post-natal surgical correction, there are also potential in-utero therapies being developed. Cyclosporin A showed promise in treating collagen VI disorders although there is an associated risk of immunosuppression. The treatments that could be in the clinical trials soon are the splice correction therapies in collagen VI-related disorders.

Label-free-based quantitative proteomic analysis of the inhibition of cisplatin-resistant ovarian cancer cell proliferation by cucurbitacin B

BACKGROUND

Ovarian cancer is a serious threat to women's health, and resistance to chemotherapeutic drugs constitutes one of the principal reasons for ovarian cancer recurrence and the low overall survival rate. Therefore, it is of paramount importance to develop additional and more-effective drugs to combat resistance to chemotherapeutic drugs. Cucurbitacin B (CuB) is a natural compound found in food plants such as bitter gourd and pumpkin, and it manifests favorable antitumor effects on a variety of malignant tumors.

PURPOSE

The present study aimed to determine the mechanism effects of CuB overcomes tumor-drug resistance in ovarian cancer.

METHODS

We used CCK-8, Edu, flow cytometric assays and cisplatin-resistant ovarian cancer xenograft mouse model to evaluate the cellular proliferation, cellular apoptosis.and tumor growth. We subsequently applied a pharmacoproteomic approach to analyze the molecular mechanisms by which CuB inhibited the proliferation of cisplatin-resistant ovarian cancer cells. We also employed western blot and molecular docking experiments to verify elements of PI3K/Akt/mTOR pathway expression.

RESULTS

We found that CuB inhibited cellular proliferation and promoted apoptosis in cisplatin-resistant ovarian cancer cell lines. We discerned that CuB inhibited tumor growth of xenograft mouse tumors. We ascertained that treatment of A2780-DDP cells with CuB resulted in the differential expression of 305 proteins, with 202 proteins downregulated and 103 proteins upregulated. Of these proteins, the mTOR protein was significantly downregulated in the drug-treated group. We also found that CuB inhibited PI3K, Akt, and mTOR and that it activated cGAS expression upstream of PI3K and inhibited ATR expression. Molecular docking experiments revealed that CuB was hydrogen-bonded to mTOR proteins at Gly (2142) and Thr (2207), with a binding force of -10.2 kcal/mol.

CONCLUSION

Our study confirmed that cucurbitacin B inhibits the PI3K/Akt/mTOR signaling pathway, targets mTOR, suppresses the proliferation of cisplatin-resistant ovarian cancer cells.And we also found that cucurbitacin B induces DNA damage, activates cGASA and recruits IKBα,playing a crucial role in eliciting anti-tumor immunity. We herein uncovered a new use for CuB in inhibiting tumor-drug resistance, providing a novel approach to overcoming chemotherapeutic drug resistance in ovarian cancer.

Screening criteria of mRNA indicators for wound age estimation

Wound age estimation is a crucial and challenging problem in forensic pathology. Although mRNA is the most commonly used indicator for wound age estimation, screening criteria are lacking. In the present study, the feasibility of screening criteria using mRNA to determine injury time based on the adenylate-uridylate-rich element (ARE) structure and gene ontology (GO) categories were evaluated. A total of 78 Sprague-Dawley male rats were contused and sampled at 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, and 48 h after inflicting injury. The candidate mRNAs were classified based on with or without ARE structure and GO category function. The mRNA expression levels were detected using qRT-PCR. In addition, the standard deviation (STD), mean deviation (MD), relative average deviation (d%), and coefficient of variation (CV) were calculated based on mRNA expression levels. The CV score (CVs) and the CV of CV (CV'CV) were calculated to measure heterogeneity. Finally, based on classic principles, the accuracy of combination of candidate mRNAs was assessed using discriminant analysis to construct a multivariate model for inferring wound age. The results of homogeneity evaluation of each group based on CVs were consistent with the MD, STD, d%, and CV results, indicating the credibility of the evaluation results based on CVs. The candidate mRNAs without ARE structure and classified as cellular component (CC) GO category (ARE-CC) had the highest CVs, showing the mRNAs with these characteristics are the most homogenous mRNAs and best suited for wound age estimation. The highest accuracy was 91.0% when the mRNAs without ARE structure were used to infer the wound age based on the discrimination model. The accuracy of mRNAs classified into CC or multiple function (MF) GO category was higher than mRNAs in the biological process (BP) category. In all subgroups, the accuracy of the composite identification model of mRNA composition without ARE structure and classified as CC was higher than other subgroups. The mRNAs without ARE structure and belonging to the CC GO category were more homogenous, showed higher accuracy for estimating wound age, and were appropriate for rat skeletal muscle wound age estimation. Supplemental data for this article is available online at https://doi.org/10.1080/20961790.2021.1986770 .

Gene Ontology Enrichment Analysis of Renal Agenesis: Improving Prenatal Molecular Diagnosis

Uni- or bilateral renal agenesis (RA) is a commonly occurring major congenital anomaly impacting fetal and neonatal outcomes. Since the etiology is highly heterogeneous, our aim was to provide a logically structured approach by highlighting the genes in which variants have been identified to be associated with RA and to define the pathways involved in this type of abnormal kidney development. We used Phenolyzer to collect a list of all the genes known as causative for RA. Using ClueGO gene enrichment analysis, we classified the relationship between these genes and the biological processes defined by gene ontology. We identified 287 genes and 69 groups of enriched biological processes. About 50% included pathways directly related to the development of urogenital organ tissues. Several ciliary, axis specification, hindgut development, and endocrine pathways were enriched, which may relate to different clinical presentations of RA. Our gene ontology enrichment analysis shows that genes representing distinct biological pathways are significantly enriched. This knowledge will lead to an improved molecular diagnosis in clinical care when applying genome-wide sequencing approaches. The findings will also allow to further study the biological pathways involved in RA and to identify novel candidate genes and pathways.

Care pathway for fetal joint contractures, Fetal Akinesia Deformation Sequence and Arthrogryposis Multiplex Congenita

Introduction The majority of arthrogryposis multiplex congenita (AMC) and lethal forms of AMC such as fetal akinesia deformation sequence (FADS) cases are missed prenatally. We have demonstrated the additional value of fetal motor assessment and evaluation in a multidisciplinary team for the period 2007-2016. An applied care pathway for fetuses presenting with joint contracture(s) in one anatomic region (e.g. talipes equinovares), more than one body part with non-progressive contractures and motility (AMC) and with deterioration over time (FADS). Methods The multidisciplinary team of Amsterdam University Medical Centre Expertise Centre FADS and AMC developed the care pathway. Additional tools are provided including a motor assessment by ultrasound examination and postmortem assessment form. Results An eight-step care pathway is presented with a proposed timing for prenatal sonographic examination, genetic examinations, multidisciplinary meetings, prenatal and postnatal counselling of the parents by specialist also treating after birth, follow-up of prenatal and postnatal findings with counselling for future pregnancies. Discussion/conclusion The scheduled serial structural and motor sonograpahic assessment together with follow-up examinations and genetic analysis, should be tailored per prenatal centre per available resources. The multidisciplinary care pathway may pave the way to increase detection rate and diagnosis of isolated contracture(s), talipes equinovares with underlying genetic causes and the rare phenotypes AMC/FADS and prompt treatment after birth within expertise teams.

Fetal akinesia deformation sequence and massive perivillous fibrin deposition resulting in fetal death in six fetuses from one consanguineous couple, including literature review

Background

Massive perivillous fibrin deposition (MPFD) is associated with adverse pregnancy outcomes and is mainly caused by maternal factors with limited involvement of fetal or genetic causes. We present one consanguineous couple with six fetuses developing Fetal Akinesia Deformation Sequence (FADS) and MPFD, with a possible underlying genetic cause. This prompted a literature review on prevalence of FADS and MPFD.

Methods

Fetal ultrasound examination, motor assessment, genetic testing, postmortem examination, and placenta histology are presented (2009–2019). Literature was reviewed for the association between congenital anomalies and MPFD.

Results

All six fetuses developed normally during the first trimester. Thereafter, growth restriction, persistent flexed position, abnormal motility, and contractures in 4/6, consistent with FADS occurred. All placentas showed histologically confirmed MPFD. Genetic analyses in the five available cases showed homozygosity for two variants of unknown significance in two genes, VARS1 (OMIM*192150) and ABCF1 (OMIM*603429). Both parents are heterozygous for these variants. From 63/1999 manuscripts, 403 fetal outcomes were mobilized. In 14/403 fetuses, congenital abnormalities in association with MPFD were seen of which two fetuses with contractures/FADS facial anomalies.

Conclusion

The low prevalence of fetal contractures/FADS facial anomalies in association with MPFD in the literature review supports the possible fetal or genetic contribution causing FADS and MPFD in our family. This study with literature review supports the finding that fetal, fetoplacental, and/or genetic components may play a role in causing a part of MPFDs.

Characterizing the molecular etiology of arthrogryposis multiplex congenita in patients with LGI4 mutations

Disruption of axon-glia interactions in the peripheral nervous system has emerged as a major cause of arthrogryposis multiplex congenita (AMC), a condition characterized by multiple congenital postural abnormalities involving the major joints. Several genes crucially important to the biology of Schwann cells have now been implicated with AMC. One such gene is LGI4 which encodes a secreted glycoprotein. LGI4 is expressed and secreted by Schwann cells and binds its receptor ADAM22 on the axonal membrane to drive myelination. Homozygous mutations in LGI4 or ADAM22 results in severe congenital hypomyelination and joint contractures in mice. Recently bi-allelic LGI4 loss of function mutations has been described in three unrelated families with severe AMC. Two individuals in a fourth, non-consanguineous family were found to be compound heterozygous for two LGI4 missense mutations. It is not known how these missense mutations affect the biology of LGI4. Here we investigated whether these missense mutations affected the secretion of the protein, its ADAM22 binding capacity, or its myelination-promoting function. We demonstrate that the mutations largely affect the progression of the mutant protein through the endomembrane system resulting in severely reduced expression. Importantly, binding to ADAM22 and myelination-promoting activity appear largely unaffected, suggesting that treatment with chemical chaperones to improve secretion of the mutant proteins might prove beneficial.

A Genomic Approach to Delineating the Occurrence of Scoliosis in Arthrogryposis Multiplex Congenita

Arthrogryposis multiplex congenita (AMC) describes a group of conditions characterized by the presence of non-progressive congenital contractures in multiple body areas. Scoliosis, defined as a coronal plane spine curvature of ≥10 degrees as measured radiographically, has been reported to occur in approximately 20% of children with AMC. To identify genes that are associated with both scoliosis as a clinical outcome and AMC, we first queried the DECIPHER database for copy number variations (CNVs). Upon query, we identified only two patients with both AMC and scoliosis (AMC-SC). The first patient contained CNVs in three genes (FBN2, MGF10, and PITX1), while the second case had a CNV in ZC4H2. Looking into small variants, using a combination of Human Phenotype Ontogeny and literature searching, 908 genes linked with scoliosis and 444 genes linked with AMC were identified. From these lists, 227 genes were associated with AMC-SC. Ingenuity Pathway Analysis (IPA) was performed on the final gene list to gain insight into the functional interactions of genes and various categories. To summarize, this group of genes encompasses a diverse group of cellular functions including transcription regulation, transmembrane receptor, growth factor, and ion channels. These results provide a focal point for further research using genomics and animal models to facilitate the identification of prognostic factors and therapeutic targets for AMC.

High Rates of Genetic Diagnosis in Psychiatric Patients with and without Neurodevelopmental Disorders: Toward Improved Genetic Diagnosis in Psychiatric Populations

OBJECTIVE

There is a paucity of literature on genetic diagnosis in psychiatric populations, particularly the vulnerable population of patients with concomitant neurodevelopmental disorder (NDD). In this cross-sectional study, we investigated the genetic diagnostic rate in 151 adult psychiatric patients from two centers in Ontario, Canada, including a large subset (73.5%) with concurrent NDD, and performed phenotypic analysis to determine the strongest predictors for the presence of a genetic diagnosis.

METHOD

Patients 16 years of age or older and affected with a psychiatric disorder plus at least one of NDD, neurological disorder, congenital anomaly, dysmorphic features, or family history of NDD were recruited through the genetics clinics between 2012 and 2016. Patients underwent genetic assessment and testing according to clinical standards. Chi-squared test was used for phenotypic comparisons. Multivariate logistic regression analysis was performed to determine which phenotypic features were predictive of genetic diagnosis types.

RESULTS

Overall, 45.7% of patients in the total cohort were diagnosed with genetic disorders with the vast majority of diagnoses (89.9%) comprising single gene and chromosomal disorders. There were management and treatment implications for almost two-thirds (63.8%) of diagnosed patients. Presence of a single gene disorder or chromosomal diagnosis was predicted by differing combinations of neurological, NDD, and psychiatric phenotypes.

CONCLUSION

The results of this study highlight the frequency and impact of genetic diagnosis in psychiatric populations, particularly those with concomitant NDD. Genetic assessment should be considered in psychiatric patients, particularly those with multiple brain phenotypes (psychiatric, neurodevelopmental, neurological).

Prenatal delineation of a distinct lethal fetal syndrome caused by a homozygous truncating KIDINS220 variant

Kinase D-interacting substrate of 220 kDa (KIDINS220) is a transmembrane protein playing integral role in growth mediating pathways in the nervous and cardiovascular systems. KIDINS220 heterozygous truncating variants that affect the protein's C-terminus have been associated with a phenotype, so far described only in few unrelated children, including spastic paraplegia, intellectual disability, nystagmus, and obesity. More recently, a homozygous, more N-terminal truncating variant in KIDINS220 gene was suggested to be associated with enlarged cerebral ventricles and limb contractures in three fetuses from a consanguineous family. We confirm the latter finding by presenting the first detailed prenatal identification of a fetal phenotype associated with novel homozygous deleterious frameshift variant in KIDINS220 gene in a consanguineous healthy Egyptian couple. History of unexplained seven miscarriages and a similar stillbirth were recorded. Prenatal ultrasonography revealed limb contractions and ventriculomegaly; in addition to previously unreported cerebellar anomalies, cardiac anomalies and hydrops fetalis. These findings represent an expansion of clinical and molecular spectrum associated with KIDINS220 variants and broaden our understanding of genotype-phenotype relationships in lethal congenital contractures syndromes and associated severe abnormal embryological development. More generally, our study adds KIDINS220 to the rare group of genes which may cause disease by either of two distinct mutational mechanisms.

Genetic diagnosis and clinical evaluation of severe fetal akinesia syndrome

Objective

In this retrospective study, we describe the clinical course, ultrasound findings and genetic investigations of fetuses affected by fetal akinesia.

Materials and Methods

We enrolled 22 eukaryotic fetuses of 18 families, diagnosed with fetal akinesia between 2008 and 2016 at the Department of Obstetrics and Feto‐Maternal Medicine at the Medical University of Vienna. Routine genetic evaluation included karyotyping and chromosomal microarray analysis. Retrospectively, exome sequencing was performed in the index case of 11 families, if stored DNA was available. Confirmation analyses and genetic diagnosis of siblings were performed by using Sanger sequencing.

Results

Whole exome sequencing identified pathogenic variants of CNTN1, RYR1, NEB, GLDN, HRAS and TNNT3 in six cases of 11 families. In three of these families, the variants were confirmed in the respective sibling.

Conclusions

The present study demonstrates a high diagnostic yield of exome sequencing in fetuses affected by akinesia syndrome, especially if family history is positive. Still, in a large part the underlying genetic cause remained unknown, whereas precise clinical evaluation in combination with exome sequencing shows to be the best tool to find the disease causing variants.

The latest FADS: Functional analysis of GLDN patient variants and classification of GLDN-associated AMC as a type of viable fetal akinesia deformation sequence

Recessive variants in the GLDN gene, which encodes the gliomedin protein and is involved in nervous system development, have recently been associated with Arthrogryposis Multiplex Congenita (AMC), a heterogenous condition characterized by congenital contractures of more than one joint. Two cohorts of patients with GLDN-associated AMC have previously been described, evolving the understanding of the condition from lethal to survivable with the provision of significant neonatal support. Here, we describe one additional patient currently living with the syndrome, having one novel variant, p.Leu365Phe, for which we provide functional data supporting its pathogenicity. We additionally provide experimental data for four other previously reported variants lacking functional evidence, including p.Arg393Lys, the second variant present in our patient. We discuss unique and defining clinical features, adding calcium-related findings which appear to be recurrent in the GLDN cohort. Finally, we compare all previously reported patients and draw new conclusions about scope of illness, with emphasis on the finding of pulmonary hypoplasia, suggesting that AMC secondary to GLDN variants may be best fitted under the umbrella of fetal akinesia deformation sequence (FADS).

Distal Arthrogryposis and Lethal Congenital Contracture Syndrome - An Overview

Distal arthrogryposis (DA) is a skeletal muscle disorder which can be classified under a broader term as Arthrogryposis multiplex contractures. DA is characterized by the presence of joint contractures at various parts of the body, particularly in distal extremities. It is identified as an autosomal dominant and a rare X-linked recessive disorder associated with increased connective tissue formation around joints in such way that immobilizes muscle movement causing deformities. DA is again classified into various types since it manifests as a range of conditions representing different etiologies. Myopathy is one of the most commonly listed etiologies of DA. The mutations in sarcomeric protein-encoding genes lead to decreased sarcomere integrity, which is often associated with this disorder. Also, skeletal disorders are often associated with cardiac disorders. Some studies mention the presence of cardiomyopathy in patients with skeletal dysfunction. Therefore, it is hypothesized that the congenitally mutated protein that causes DA can also lead to cardiomyopathy. In this review, we will summarize the different forms of DA and their clinical features, along with gene mutations responsible for causing DA in its different forms. We will also examine reports that list mutations also known to cause heart disorders in the presence of DA.

The Novel Compound Heterozygous Mutations of ECEL1 Identified in a Family with Distal Arthrogryposis Type 5D

Introduction

Distal arthrogryposis type 5D (DA5D) is an autosomal recessive disease. The clinical symptoms include contractures of the joints of limbs, especially camptodactyly of the hands and/or feet, unilateral ptosis, a round-shaped face, arched eyebrows, and micrognathia, without ophthalmoplegia. ECEL1 is a DA5D causative gene that encodes a membrane-bound metalloprotease. ECEL1 plays important roles in the final axonal arborization of motor nerves in limb skeletal muscles and neuromuscular junction formation during prenatal development.

Methods

A DA5D family with webbing of the elbows and fingers was recruited. We performed whole-exome sequencing (WES) and filtered mutations by disease-causing genes of arthrogryposis multiplex congenita (AMC). Mutational analysis and cosegregation confirmation were then performed.

Results

We identified novel compound heterozygous mutations of ECEL1 (NM_004826: c.69C>A, p.C23∗ and c.1810G>A, p.G604R) in the proband.

Conclusions

We detected causative mutations in a DA5D family, expanding the spectrum of known ECEL1 mutations and contributing to the clinical diagnosis of DA5D.

Orthopaedic care of the child with arthrogryposis: a 2020 overview

PURPOSE OF REVIEW

The orthopaedic treatment of children with arthrogryposis multiplex congenita has evolved steadily over the past two decades. Interrelated factors have spurred this on, including better appreciation of the functional potential of persons with arthrogryposis, development of newer procedures specific for the arthrogrypotic deformities, and outcomes studies that provide understanding of the overall capabilities of adults with arthrogryposis and follow-up to determine which treatments were beneficial and which were not. This article briefly sketches out of some of these advances and indicates areas that need further development.

RECENT FINDINGS

Outcome studies show that the majority of adults with arthrogryposis are ambulatory but less than half are fully independent. Adults frequently experience ongoing pain, particularly foot and back pain, limiting ambulation and standing. Advancements in the upper extremity treatment include improving elbow function, wrist repositioning, and improving thumb positioning. In the lower extremities, correction of hip and knee contractures leads to improved ambulatory potential, and treating clubfeet with serial casting decreases poor outcomes.

SUMMARY

Clinical evaluation, both physical examination and assessment of the patient's needs, are important in directing treatment in arthrogryposis. Further outcomes studies are needed to continue to refine procedures and define the appropriate candidates.

Orthopedic findings in arthrogryposis and congenital Zika syndrome: A case series

BACKGROUND

Congenital arthrogryposis (CA) consists of congenital joint contractures that affect at least two joints in different parts of the body. Approximately, 80% of CA cases are neurogenic, with changes to the formation, structure or functioning of the central and/or peripheral nervous systems. Most abnormalities are triggered either by motoneurons decreased activation in the corticospinal tract or by direct motoneurons injury. There had been few reports in the literature correlating congenital infection in humans with arthrogryposis until 2015. CA has recently been described associated with congenital Zika syndrome (CZS).

METHODS

The objective of this study was to investigate and describe accurately the arthrogrypotic alterations in infants diagnosed with CZS and thus, suggest a possible pattern of orthopedic impairment. A total of 198 medical records of infants with CZS were evaluated. According to inclusion and exclusion criteria, 17 infants were included in the present study. Arthrogrypotic joints were orthopedically evaluated in four segments: right, left, upper, and lower limbs. All the four segments were assessed independently.

RESULTS

Flexed wrists were the most frequently observed manifestation, associated with ulnar deviation (35.29%). Deformities were also commonly found in the third and fourth fingers (64.70%). Hip dislocation was found in 58.82% of the patients and talipes equinovarus and equinovalgus ankles were found in 29.41 and 23.52%.

CONCLUSION

There was a particular pattern of joint impairment related to CZS and arthogrypotic alterations of infants evaluated in this study.

A novel de novo nonsense mutation in ZC4H2 causes Wieacker-Wolff Syndrome

Background

Wieacker‐Wolff syndrome (WWS) is a congenital X‐linked neuromuscular disorder, which was firstly reported in 1985. Zinc finger C4H2‐type containing (ZC4H2) gene has been found to be associated with the disease pathogenesis. However, the underlying mechanism remains elusive.

Methods

Whole‐exome sequencing was performed to identify the mutations. Expression plasmids were constructed and cell culture and immune‐biochemical assays were used to examine the effects of the mutation.

Results

We reported a female patient with classical symptoms of WWS and discovered a novel nonsense heterozygous mutation (p.R67X; c.199C>T) in ZC4H2 gene in the patient but not in her parents. The mutation resulted in a 66 amino‐acid truncated ZC4H2 protein. The mutation is located in the key helix domain and it altered the subcellular locations of the mutant ZC4H2 protein. X‐chromosome inactivation (XCI) pattern analysis revealed that the XCI ratio of the proband was 22:78.

Conclusion

Female heterozygous carriers with nonsense mutation with a truncated ZC4H2 protein could lead to the pathogenesis of Wieacker‐Wolff syndrome and our study provides a potential new target for the disease treatment.

Exome reports A de novo GNB2 variant associated with global developmental delay, intellectual disability, and dysmorphic features

Heterotrimeric G proteins are composed of α, β, and γ subunits and are involved in integrating signals between receptors and effector proteins. The 5 human Gβ proteins (encoded by GNB1, GNB2, GNB3, GNB4, and GNB5) are highly similar. Variants in GNB1 were identified as a genetic cause of developmental delay. De novo variant in GNB2 has recently been reported as a cause of sinus node dysfunction and atrioventricular block but not as a cause of developmental delay. Trio-based whole-exome sequencing was performed on an individual with global developmental delay, muscle hypotonia, multiple congenital joint contractures and dysmorphism such as brachycephalus, thick eyebrows, thin upper lip, micrognathia, prominent chin, and bilateral tapered fingers. We identified a de novo GNB2 variant c.229G>A, p.(Gly77Arg). Notably, pathogenic substitutions of the homologous Gly77 residue including an identical variant (p.Gly77Arg, p.Gly77Val, p.Gly77Ser, p.Gly77Ala) of GNB1, a paralog of GNB2, was reported in individuals with global developmental delay and hypotonia. Clinical features of our case overlap with those of GNB1 variants. Our study suggests that a GNB2 variant may be associated with syndromic global developmental delay.

The genomic and clinical landscape of fetal akinesia

PURPOSE

Fetal akinesia has multiple clinical subtypes with over 160 gene associations, but the genetic etiology is not yet completely understood.

METHODS

In this study, 51 patients from 47 unrelated families were analyzed using next-generation sequencing (NGS) techniques aiming to decipher the genomic landscape of fetal akinesia (FA).

RESULTS

We have identified likely pathogenic gene variants in 37 cases and report 41 novel variants. Additionally, we report putative pathogenic variants in eight cases including nine novel variants. Our work identified 14 novel disease-gene associations for fetal akinesia: ADSSL1, ASAH1, ASPM, ATP2B3, EARS2, FBLN1, PRG4, PRICKLE1, ROR2, SETBP1, SCN5A, SCN8A, and ZEB2. Furthermore, a sibling pair harbored a homozygous copy-number variant in TNNT1, an ultrarare congenital myopathy gene that has been linked to arthrogryposis via Gene Ontology analysis.

CONCLUSION

Our analysis indicates that genetic defects leading to primary skeletal muscle diseases might have been underdiagnosed, especially pathogenic variants in RYR1. We discuss three novel putative fetal akinesia genes: GCN1, IQSEC3 and RYR3. Of those, IQSEC3, and RYR3 had been proposed as neuromuscular disease-associated genes recently, and our findings endorse them as FA candidate genes. By combining NGS with deep clinical phenotyping, we achieved a 73% success rate of solved cases.

Arthrogryposis multiplex congenita definition: Update using an international consensus-based approach

Arthrogryposis multiplex congenita (AMC) has been described and defined in thousands of articles, but the terminology used has been inconsistent. Some have described it as a diagnosis or syndrome, others as a term or clinical finding. This lack of common language can lead to confusion in clinical and research communities. The aim of this study was to develop a consensus-based definition for AMC using international expert opinion. A consensus-based definition will help harmonize research and clinical endeavors and will facilitate communication among families, clinicians, and researchers. This article describes the methodology used leading to a proposed definition of AMC. First, a literature review was conducted to identify AMC definitions used in included studies. The most commonly used words in the definitions were extracted. Second, a group of eight experts in AMC was selected to identify elements considered critically important to the definition of AMC. Third, based on these critical elements and the literature review, a definition was drafted by the research team. Fourth, a modified Delphi consensus process was conducted using electronic surveys with 25 experts in the field of AMC from eight countries. Survey results were analyzed quantitatively and qualitatively and drafts were modified accordingly. Three rounds of surveys were completed until consensus was reached on a definition of AMC. An annotation of this definition, developed by a panel of international experts, is provided in a separate manuscript in this special issue.

Central nervous system involvement in arthrogryposis multiplex congenita: Overview of causes, diagnosis, and care

Arthrogryposis or AMC, arthrogryposis multiplex congenita, is defined as multiple congenital joint contractures in more than two joints and in different body areas. The common cause of all AMC is lack of movement in utero, which in turn can have different causes, one of which is CNS involvement. Intellectual disability/CNS involvement is found in approximately 25% of all AMC. AMC with CNS involvement includes a large number of genetic syndromes. So far, more than 400 genes have been identified as linked to AMC, with and without CNS involvement. A number of neonatally lethal syndromes and syndromes resulting in severe disability due to CNS malfunction belong to this group of syndromes. There are several X-linked disorders with AMC, which are primarily related to intellectual disability. A number of neuromuscular disorders may include AMC and CNS/brain involvement. Careful clinical evaluation by a geneticist and a pediatrician/pediatric neurologist is the first step in making a specific diagnosis. Further investigations may include MRI of the brain and spinal cord, electroencephalogram, blood chemistry for muscle enzymes, other organ investigations (ophtalmology, cardiology, gastrointestinal, and genitourinary systems). Nerve conduction studies, electromyogram, and muscle pathology may be of help when there is associated peripheral nervous system involvement. But most importantly, genetic investigations with targeted or rather whole exome or genome sequencing should be performed. A correct diagnosis is important in planning adequate treatment, in genetic counselling and also for future understanding of pathogenic mechanisms and possible new treatments. A multidiciplinary team is needed both in investigation and treatment.

A standardized autopsy protocol for arthrogryposis (multiple congenital contractures)

Arthrogryposis multiplex congenita (AMC) describes disorders with multiple joint contractures that arise from neurological, neuromuscular, or mechanical origin. Although impaired fetal movement is the typical clinical presentation, the etiology underlying this phenotype for a number of conditions remains unknown. In an effort to better characterize and define the etiologies underlying these disorders, we recommend a standardized autopsy protocol that will allow for appropriate diagnosis and a methodical approach for examination that will facilitate subsequent study by investigators across disciplines. To further support investigation, we have also established an AMC autopsy registry to bank tissue obtained at autopsy for subsequent study.

Gene ontology analysis of arthrogryposis (multiple congenital contractures)

In 2016, we published an article applying Gene Ontology Analysis to the genes that had been reported to be associated with arthrogryposis (multiple congenital contractures) (Hall & Kiefer, 2016). At that time, 320 genes had been reported to have mutations associated with arthrogryposis. All were associated with decreased fetal movement. These 320 genes were analyzed by biological process and cellular component categories, and yielded 22 distinct groupings. Since that time, another 82 additional genes have been reported, now totaling 402 genes, which when mutated, are associated with arthrogryposis (arthrogryposis multiplex congenita). So, we decided to update the analysis in order to stimulate further research and possible treatment. Now, 29 groupings can be identified, but only 19 groups have more than one gene.

Research platform for children with arthrogryposis multiplex congenita: Findings from the pilot registry

A pediatric registry for arthrogryposis multiplex congenita (AMC) proposes to advance research by providing the platform to inform the distribution, etiology, and natural history of AMC. The registry was piloted on 40 families of children (mean = 8.25 years, 48% males) presenting with AMC across two hospitals in North America. Data on the child's demographic and newborn variables, mothers' and fathers' demographic variables, lifestyle habits, and medical history were collected using a telephone interview with the primary caregiver and review of medical charts. Mean gestational age was 38 weeks, 97% of children presented with lower extremity deformities, and 74% of neonatal interventions targeted the lower extremity. Newborns spent an average of 14 days in the hospital (range 2-56 days) mostly for diagnostic workup and feeding difficulties. Half (49%) of the sample had internal organ involvement. Genetic testing was done on 48% of the children, including chromosome studies, single gene, whole-exome/genome sequencing, and/or microarray studies. Genetic findings were inconclusive in most. Two-thirds of mothers (67%) reported inconsistently feeling fetal movements. This pilot study contributed to the refinement of participant selection, identification of data source, expansion of data sets, and areas for future exploration prior to the implementation of a multisite AMC pediatric registry.

Fetal arthrogryposis: Challenges and perspectives for prenatal detection and management

Antenatal identification of fetuses with multiple congenital contractures or arthrogryposis multiplex congenita (AMC) may be challenging. The first clinical sign is often reduced fetal movement and/or contractures, as seen on prenatal ultrasounds. This can be apparent at any point, from early to late pregnancy, may range from mild to severe involvement, with or without associated other structural anomalies. Possible etiologies and their prognosis need to be interpreted with respect to developmental timing. The etiology of AMC is highly heterogeneous and making the specific diagnosis will guide prognosis, counseling and prenatal and perinatal management. Current ultrasound practice identifies only approximately 25% of individuals with arthrogryposis prenatally before 24 weeks of pregnancy in a general obstetrics care population. There are currently no studies and guidelines that address the question of when and how to assess for fetal contractures and movements during pregnancy. The failure to identify fetuses with arthrogryposis before 24 weeks of pregnancy means that physicians and families are denied reproductive options and interventions that may improve outcome. We review current practice and recommend adjusting the current prenatal imaging and genetic diagnostic strategies to achieve early prenatal detection and etiologic diagnosis. We suggest exploring options for in utero therapy to increase fetal movement for ongoing pregnancies.

Fetal arthrogryposis multiplex congenita/fetal akinesia deformation sequence (FADS)-Aetiology, diagnosis, and management

Arthrogryposis multiplex congenita (AMC) refers to an aetiologically heterogenous condition, which consists of joint contractures affecting two or more joints starting prenatally. The incidence is approximately one in 3000 live births; however, the prenatal incidence is higher, indicating a high intrauterine mortality. Over 320 genes have been implicated showing the genetic heterogeneity of the condition. AMC can be of extrinsic aetiology resulting from intrauterine crowding secondary to congenital structural uterine abnormalities (eg, bicornuate or septate uterus), uterine tumors (eg, fibroid), or multifetal pregnancy or intrinsic/primary/fetal aetiology, due to functional abnormalities in the brain, spinal cord, peripheral nerves, neuromuscular junction, muscles, bones, restrictive dermopathies, tendons and joints. Unlike many of the intrinsic/primary/fetal causes which are difficult to treat, secondary AMC can be treated by physiotherapy with good response. Primary cases may present prenatally with fetal akinesia associated with joint contractures and occasionally brain abnormalities, decreased muscle bulk, polyhydramnios, and nonvertex presentation while the secondary cases usually present with isolated contractures. Complete prenatal and postnatal investigations are needed to identify an underlying aetiology and provide information regarding its prognosis and inheritance, which is critical for the obstetrical care providers and families to optimize the pregnancy management and address future reproductive plans.

International multidisciplinary collaboration toward an annotated definition of arthrogryposis multiplex congenita

Arthrogryposis multiplex congenita (AMC) has been described and defined in thousands of articles, but the terminology used has been inconsistent in clinical and research communities. A definition of AMC was recently developed using a modified Delphi consensus method involving 25 experts in the field of AMC from 8 countries. Participants included health care professionals, researchers, and individuals with AMC. An annotation of the definition provides more in-depth explanations of the different sentences of the AMC definition and is useful to complement the proposed definition. The aim of this study was to provide an annotation of the proposed consensus-based AMC definition. For the annotation process, 17 experts in AMC representing 10 disciplines across 7 countries participated. A paragraph was developed for each sentence of the definition using an iterative process involving multiple authors with varied and complementary expertise, ensuring all points of view were taken into consideration. The annotated definition provides an overview of the different topics related to AMC and is intended for all stakeholders, including youth and adults with AMC, their families, and clinicians and researchers, with the hopes of unifying the understanding of AMC in the international community.

The Genomics of Arthrogryposis, a Complex Trait: Candidate Genes and Further Evidence for Oligogenic Inheritance

Arthrogryposis is a clinical finding that is present either as a feature of a neuromuscular condition or as part of a systemic disease in over 400 Mendelian conditions. The underlying molecular etiology remains largely unknown because of genetic and phenotypic heterogeneity. We applied exome sequencing (ES) in a cohort of 89 families with the clinical sign of arthrogryposis. Additional molecular techniques including array comparative genomic hybridization (aCGH) and Droplet Digital PCR (ddPCR) were performed on individuals who were found to have pathogenic copy number variants (CNVs) and mosaicism, respectively. A molecular diagnosis was established in 65.2% (58/89) of families. Eleven out of 58 families (19.0%) showed evidence for potential involvement of pathogenic variation at more than one locus, probably driven by absence of heterozygosity (AOH) burden due to identity-by-descent (IBD). RYR3, MYOM2, ERGIC1, SPTBN4, and ABCA7 represent genes, identified in two or more families, for which mutations are probably causative for arthrogryposis. We also provide evidence for the involvement of CNVs in the etiology of arthrogryposis and for the idea that both mono-allelic and bi-allelic variants in the same gene cause either similar or distinct syndromes. We were able to identify the molecular etiology in nine out of 20 families who underwent reanalysis. In summary, our data from family-based ES further delineate the molecular etiology of arthrogryposis, yielded several candidate disease-associated genes, and provide evidence for mutational burden in a biological pathway or network. Our study also highlights the importance of reanalysis of individuals with unsolved diagnoses in conjunction with sequencing extended family members.

Biallelic deletions of the Waardenburg II syndrome gene, SOX10, cause a recognizable arthrogryposis syndrome

Random mating in the general population tends to limit the occurrence of homozygous and compound heterozygous forms of dominant hereditary disorders. Certain phenotypes, the most recognized being skeletal dysplasias associated with short stature, lead to cultural interaction and assortative mating. To this well-known example, may be added deafness which brings together individuals with a variety of deafness genotypes, some being dominant. Waardenburg syndrome is one such autosomal dominant disorder in which affected individuals may interact culturally because of deafness. Biallelic genetic alterations for two Waardenburg genes, PAX3 and MITF have been previously recognized. Herein, we report biallelic deletions in SOX10, a gene associated with Waardenburg syndromes type II and IV. The affected fetuses have a severe phenotype with a lack of fetal movement resulting in four-limb arthrogryposis and absence of palmar and plantar creases, white hair, dystopia canthorum, and in one case cleft palate and in the other a cardiac malformation.

Arthrogryposis in children: Etiological assessments and preparation of a protocol for etiological investigations

INTRODUCTION

Arthrogryposis is a descriptive term defining a sign. It describes a set of joint contractures, sometimes identifiable in utero, present from birth and nonprogressive. This term includes a heterogeneous group of diseases, of neurological, neuromuscular, genetic or mechanical origin. The common physiopathological mechanism is fetal immobility syndrome. Two types of classification have been developed: a clinical one (types I, II and III) and an etiological one. The main aim of this study was to define a standardized protocol for etiological investigation based on a descriptive analysis of the various etiologies identified in a population of children followed up for arthrogryposis. Its secondary aim was to assess first the comprehensiveness and relevance of the complementary assessment and second the way in which the classifications proposed by Professor Judith Goslin Hall are applied.

MATERIAL AND METHODS

Retrospective multicenter observational study. We enrolled pediatric patients with arthrogryposis being treated at a reference center for neuromuscular diseases, i.e., in three university hospital pediatric neurology units, between February 1997 and January 2017.

RESULTS

Forty-two patients (25 boys and 17 girls) were enrolled. According to the clinical classification (Hall et al.), this population consisted of eight cases of type 1 arthrogryposis (19.1%), 14 type II (33.3%) and 20 type III (47.6%). The main etiology was neurological (19.1%), predominantly involving problems with gyration of a polymicrogyria type. Myopathic origin accounted for 9.5% of the population, predominantly involving genotyped distal arthrogryposis (ECEL1 gene). Additional tests produced a diagnosis of 25% type I, 43% type II and 75% type III.

CONCLUSION

Arthrogryposis is a sign suggesting multiple etiologies. The main ones are neurological. Several genes have recently been identified, explaining the physiopathological mechanisms. The diagnostic process must be rigorous and coordinated within a multidisciplinary team, following a shared protocol for analysis.

A severe female case of arthrogryposis multiplex congenita with brain atrophy, spastic quadriplegia and intellectual disability caused by ZC4H2 mutation

Arthrogryposis multiplex congenita (AMC) is characterized by heterogeneous multiple congenital contractures appearing at birth. Mutations in X-linked zinc-finger gene ZC4H2 were recently identified in some families and individuals with variable forms of AMC associated with dysmorphic signs, intellectual disability and spastic paresis. We present a non-consanguineous Japanese female presenting AMC with severe intellectual disability and spastic quadriplegia who also had progressive brain atrophy. Microarray-based comparative genomic hybridization identified 395 kb microdeletions at Xq11.2 which only included ZC4H2 gene. Previous reports showed that affected females have lesser symptoms and slight abnormality on brain MRI compared to male due to X-inactivation. Our case, however, showed severe manifestation than as ever reported as well as progressive diffuse brain atrophy, which implicated contribution of other genetic or environmental factors or extremely skewed X inactivation.

Genetics and Classifications

Arthrogryposis multiplex congenital (AMC) is a descriptive term for a group of conditions that all share the characteristic of congenital contractures. There are an estimated 400 discrete diagnoses that can lead to a child being born with arthrogryposis. The 2 biggest categories of conditions are amyoplasia and distal arthrogryposis, which combined make up ∼50% to 65% of all diagnoses within the AMC subset. Amyoplasia, the most common AMC condition, seems to be a nongenetic syndrome, leading to very characteristic upper and lower limb contractures. The distal arthrogryposes, in contrast, have an underlying genetic abnormality, which in many cases seems to target the fast twitch muscles of the developing fetus. Classifying AMC is a difficult task, given the broad range of conditions represented. Four different classification schemes are presented.

Arthrogryposis multiplex congenita in utero: radiologic and pathologic findings

Arthrogryposis multiplex congenita (AMC) refers to the development of multiple joint contractures affecting two or more areas of the body prior to birth. It affects approximately 1 in 3000 individuals, mostly reported in individuals of Asian, African and European descent with equal incidence in males and females. Arthrogryposis is associated with over 400 medical conditions and 350 known genes with considerable variability in phenotypic expression. The primary underlying mechanism is decreased fetal movement during development. Prenatal imaging is crucial in early diagnosis by identifying fetal movement limitations and the presence of club foot or joint contractures. Postnatal autopsy confirms the diagnosis and extent of associated congenital anomalies and provides a valuable source of DNA material. Molecular methods are particularly useful in delineating novel gene mutations, locus heterogeneity and phenotype genotype correlation. Prenatal evaluation with early diagnosis via image scanning and further genetic surveillance give the opportunity for family counseling concerning future pregnancy management and expected neonatal morbidity and mortality.

The Clinic Is My Laboratory: Life as a Clinical Geneticist

Clinical genetics is the application of advances in genetics and medicine to real human families. It involves diagnosis, care, and counseling concerning options available to affected individuals and their family members. Advances in medicine and genetics have led to dramatic changes in the scope and responsibilities of clinical genetics. This reflection on the last 50+ years of clinical genetics comes from personal experience, with an emphasis on the important contributions that clinical geneticists have made to the understanding of disease/disorder processes and mechanisms. The genetics clinic is a research laboratory where major advances in knowledge can and have been made.

Survival among children with "Lethal" congenital contracture syndrome 11 caused by novel mutations in the gliomedin gene (GLDN)

Biallelic GLDN mutations have recently been identified among infants with lethal congenital contracture syndrome 11 (LCCS11). GLDN encodes gliomedin, a protein required for the formation of the nodes of Ranvier and development of the human peripheral nervous system. We report six infants and children from four unrelated families with biallelic GLDN mutations, four of whom survived beyond the neonatal period into infancy, childhood, and late adolescence with intensive care and chronic respiratory and nutritional support. Our findings expand the genotypic and phenotypic spectrum of LCCS11 and demonstrate that the condition may not necessarily be lethal in the neonatal period.

Mutations in ERGIC1 cause Arthrogryposis multiplex congenita, neuropathic type

Arthrogryposis multiplex congenita (AMC) is heterogeneous group of disorders characterized by non-progressive joint contractures from birth that involve more than 1 part of the body. There are various etiologies for AMC including genetic and environmental depends on the specific type, however, for most types, the cause is not fully understood. We previously reported large Israeli Arab kindred consisting of 16 patients affected with AMC neuropathic type, and mapped the locus to a 5.5 cM interval on chromosome 5qter. Using whole exome sequencing, we have now identified homozygous pathogenic variant in the ERGIC1 gene within the previously defined linked region. ERGIC1 encodes a cycling membrane protein which has a possible role in transport between endoplasmic reticulum and Golgi. We further show that this mutation was absent in more than 200 samples of healthy unrelated individuals of the Israeli Arab population. Thus, our findings expand the spectrum of hereditary AMC and suggest that abnormalities in protein trafficking may underlie AMC-related disorders.