Clinical and Genetic Findings in a Series of Eight Families with Arthrogryposis

Perinatal genetic diagnostic yield in a population of fetuses with the phenotype arthrogryposis multiplex congenita: a cohort study 2007-2021

Arthrogryposis multiplex congenita (AMC) presents challenges for prenatal detection due to its heterogeneous etiology, onset, and phenotypical manifestations. This study aims to describe the genetic diagnostic yield in a population of fetuses with detailed phenotypic description over a 15-year period (2007-2021) at the Fetal Medicine Unit of Amsterdam UMC, the Netherlands. The fetal and neonatal phenotypes were classified into three clinical AMC Groups, with the exception that Groups 1 and 2 were combined in the prenatal classification. Group 1 involves limb involvement primarily, Group 2 includes musculoskeletal involvement plus other system anomalies, and Group 3 involves musculoskeletal involvement with central nervous system disability, lethality, fetal akinesia deformation sequence, and/or intellectual disability. The cohort consisted of 64 consecutive cases, 13 in Groups 1 + 2 and 51 in Group 3. Perinatal genetic testing occurred in all cases: prenatally in 56 of the 64 (88%), postnatally in 36 of the 64 (56%), and combined testing in 28 of the 64 cases (44%). The overall genetic diagnostic yield was 28% (18/64), and it increased over the 5-year period from 14% to 50%. Whole exome sequencing had the highest yield (41.7%). The yield per phenotype was 30.8% (4/13) for AMC Group 1 + 2 and 27.4% (14/51) for AMC Group 3. Detailed fetal phenotyping and perinatal genetic testing in all cases showed improved diagnostic yield over time, likely due to the introduction of Next-generation sequencing-based tests. The availability of stored DNA will be beneficial for future investigations since further improvements in genetic testing possibilities are expected.

Maternal, fetal and neonatal outcomes among pregnant women with arthrogryposis multiplex congenita: a scoping review

BACKGROUND

The rarity of pregnancies in women with arthrogryposis multiplex congenita (AMC) could lead to healthcare providers having limited exposure to these cases. Consequently, they may be less familiar with the possibilities and challenges associated with pregnancies in women affected by AMC. AMC is an umbrella term for a disorder with multiple contractures at birth, having a broad spectrum of causes, onset and severity of expression. A clinical classification describing the phenotype is Group 1 with primary limb involvement, Group 2 with musculoskeletal involvement plus other system anomalies, and Group 3 with musculoskeletal involvement plus central nervous system dysfunction and/or intellectual disability. A scoping review was conducted to review available literature on documented cases of pregnancies in women with AMC, with the following aims: (1) to outline the maternal, fetal and neonatal outcomes; (2) to describe AMC stability during and after pregnancy (worsening of symptoms due to contractures, increased muscle weakness, pain or lung involvement); and (3) to summarize counselling aspects during pregnancy for expecting mothers who have AMC.

RESULTS

This scoping review included 27 manuscripts reporting on 43 women with 82 pregnancies, of whom 18 in Group 1, 20 in Group 2, 2 in Group 3, and 3 with an unknown type. Details on pregnancy-related outcomes could be depicted from 26 of the 43 women concerning 31 pregnancies. Among these pregnancies, 74% (23/31) had a cesarean section delivery, of which 74% (17/23) were elective. Children were born preterm before week 37 in 7 of 31 pregnancies (22%). A birth weight below the 10th percentile was seen in 6 of the 24 (25%) with a reported birth weight. The course of the pregnancy was uneventful in 16 of the 26 women (62%). Pregnancy had a limited negative influence on AMC stability except for three cases with a transient worsening of lung function.

CONCLUSIONS

Gathering the information of the case histories revealed that the majority of the reported women had Distal Arthrogryposis with stable AMC during pregnancy and after delivery. The risk to have a cesarean section, preterm labour or a small for gestational age child is higher in this group than in the general population. Insights obtained by this review emphasized to offer (pre)pregnancy counselling and care by a multidisciplinary team tailored to the women's type of AMC, to ensure optimal preparation for both obstetric, genetic, neurologic, pulmonary and anesthetic care during pregnancy, delivery and postpartum period.

Transcriptional Changes Associated with Amyoplasia

Arthrogryposis, which represents a group of congenital disorders, includes various forms. One such form is amyoplasia, which most commonly presents in a sporadic form in addition to distal forms, among which hereditary cases may occur. This condition is characterized by limited joint mobility and muscle weakness, leading to limb deformities and various clinical manifestations. At present, the pathogenesis of this disease is not clearly understood, and its diagnosis is often complicated due to significant phenotypic diversity, which can result in delayed detection and, consequently, limited options for symptomatic treatment. In this study, a transcriptomic analysis of the affected muscles from patients diagnosed with amyoplasia was performed, and more than 2000 differentially expressed genes (DEGs) were identified. A functional analysis revealed disrupted biological processes, such as vacuole organization, cellular and aerobic respiration, regulation of mitochondrion organization, cellular adhesion, ATP synthesis, and others. The search for key nodes (hubs) in protein-protein interaction networks allowed for the identification of genes involved in mitochondrial processes.

Heterogenic Genetic Background of Distal Arthrogryposis-Review of the Literature and Case Report

Distal arthrogryposis (DA) is a skeletal muscle disorder that is characterized by the presence of joint contractures in various parts of the body, particularly in the distal extremities. In this study, after a systematic review of the literature, we present a case report of a non-consanguineous family. In our case, the first-trimester ultrasound was negative, and the presence of the affected mother was not enough for the parents to consent to us performing invasive amniotic fluid sampling. The second-trimester ultrasound showed clear abnormalities suggestive of arthrogryposis. Whole-exome sequencing was performed and an autosomal dominantly inherited disease-associated gene was identified. In our case, a pathogenic variant in the TNNT3 gene c.188G>A, p.Arg63His variant was identified. The mother, who had bilateral clubfoot and hand involvement in childhood, carried the same variant. The TNNT3 gene is associated with distal arthrogryposis type 2B2, which is characterized by congenital contractures of the distal limb joints and facial dysmorphism. In the ultrasound, prominent clubfoot was identified, and the mother, who also carried the same mutation, had undergone surgeries to correct the clubfoot, but facial dysmorphism was not detected. Our study highlights the importance of proper genetic counseling, especially in an affected parent(s), and close follow-up during pregnancy.

Arthrogryposis multiplex congenita: dental and maxillofacial phenotype - A scoping review

INTRODUCTION

Arthrogryposis multiplex congenita (AMC) is a heterogeneous group of disorders associated with decreased fetal movement, with a prevalence between 1/3000 and 1/5200 live births. Typical features of AMC include multiple joint contractures present at birth, and can affect all joints of the body, from the jaw, and involving the upper limbs, lower limbs and spine. The jaws may be affected in 25 % of individuals with AMC, with limited jaw movement and mouth opening. Other oral and maxillofacial deformities may be present in AMC, including cleft palate, micrognathia, periodontitis and delayed teething. To our knowledge, oral and maxillofacial abnormalities have not been systematically assessed in individuals with AMC. Therefore, this scoping review was conducted to identify, collect, and describe a comprehensive map of the existing knowledge on dental and maxillofacial involvement in individuals with AMC.

METHODOLOGY

A scoping review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews guidelines. The PRISMA guidelines for scoping reviews were followed and databases were searched for empirical articles in English and French published until October 2022. We searched MEDLINE, Embase, Web of Science and ERIC databases. Two authors independently reviewed the articles and extracted the data.

RESULTS

Of a total of 997 studies that were identified, 96 met the inclusion criteria and were subsequently included in this scoping review. These 96 studies collectively provided insights into 167 patients who exhibited some form of oral and/or maxillofacial involvement. Notably, 25 % of these patients were within the age range of 0-6 months. It is worth highlighting that only 22 out of the 96 studies (22.9 %), had the primary objective of evaluating dental and/or maxillofacial deformities. Among the patients studied, a prevalent pattern emerged, revealing that severe anomalies such as micrognathia (56 %), high-arched palate (29 %), cleft palate (40 %), limited mouth opening (31 %), and dental anomalies (28 %) were frequently observed. Importantly, many of these patients were found to have more than one of these anomalies. Even though these maxillofacial impairments are known to be associated with dental problems (e.g., cleft palate is associated with oligodontia, hypodontia, and malocclusion), their secondary effects on the dental phenotype were not reported in the studies.

CONCLUSION

Our findings have uncovered a notable deficiency in existing literature concerning dental and maxillofacial manifestations in AMC. This underscores the need for interdisciplinary collaboration and the undertaking of extensive prospective cohort studies focused on AMC. These studies should assess the oral and maxillofacial abnormalities that can impact daily functioning and overall quality of life.

A novel compound heterozygous variant of ECEL1 induced joint dysfunction and cartilage degradation: a case report and literature review

Background

Distal arthrogryposis type 5D (DA5D) represents a subtype of distal arthrogryposis (DA) characterized by congenital joint contractures in the distal extremities. DA5D is inherited in a rare autosomal recessive manner and is associated with the ECEL1 gene. In this report, we describe a case of an infant with bilateral knee contractures and ptosis, caused by a novel compound heterozygous mutation of ECEL1.

Case presentation

We conducted DNA extraction, whole-exome sequencing analysis, and mutation analysis of ECEL1 to obtain genetic data on the patient. We subsequently analyzed the patient's clinical and genetic data. The proband was a 6 months-old male infant who presented with significant bilateral knee contracture disorders and bilateral ptosis. MRI demonstrated cartilage degradation in knee joint. Whole-exome sequencing of the patient's DNA revealed a compound heterozygous mutation of c.2152-15C>A and c.110_155del in ECEL1. Analysis with the MutationTaster application indicated that c.110_155del was pathogenic (probability = 1), causing frameshift mutations affecting 151 amino acids (p.F37Cfs*151). The truncated protein lost the substructure of a transmembranous site based on the predicted protein crystal structure AF-O95672-F1. The variant of c.2152-15C>A of ECEL1 was also predicted to be disease-causing (probability = 0.98) as it impaired the methylation of ECEL1 serving as an H3K27me3 modification site, which led to the dysfunction of the second topological domain. Therefore, we concluded that the compound heterozygous mutation caused the pathogenic phenotype of this proband.

Conclusion

The present case highlights the usefulness of molecular genetic screening in diagnosing unexpected joint disorder. Identification of novel mutations in the ECEL1 gene broadens the mutation spectrum of this gene and adds to the genotype-phenotype map of DA5D. Furthermore, rapid whole-exome sequencing analysis enabled timely diagnosis of this rare disease, facilitating appropriate treatment and scheduled follow-up to improve clinical outcomes.

The crucial role of titin in fetal development: recurrent miscarriages and bone, heart and muscle anomalies characterise the severe end of titinopathies spectrum

BACKGROUND

Titin truncating variants (TTNtvs) have been associated with several forms of myopathies and/or cardiomyopathies. In homozygosity or in compound heterozygosity, they cause a wide spectrum of recessive phenotypes with a congenital or childhood onset. Most recessive phenotypes showing a congenital or childhood onset have been described in subjects carrying biallelic TTNtv in specific exons. Often karyotype or chromosomal microarray analyses are the only tests performed when prenatal anomalies are identified. Thereby, many cases caused by TTN defects might be missed in the diagnostic evaluations. In this study, we aimed to dissect the most severe end of the titinopathies spectrum.

METHODS

We performed a retrospective study analysing an international cohort of 93 published and 10 unpublished cases carrying biallelic TTNtv.

RESULTS

We identified recurrent clinical features showing a significant correlation with the genotype, including fetal akinesia (up to 62%), arthrogryposis (up to 85%), facial dysmorphisms (up to 73%), joint (up to 17%), bone (up to 22%) and heart anomalies (up to 27%) resembling complex, syndromic phenotypes.

CONCLUSION

We suggest TTN to be carefully evaluated in any diagnostic process involving patients with these prenatal signs. This step will be essential to improve diagnostic performance, expand our knowledge and optimise prenatal genetic counselling.

Novel Arthrogryposis Multiplex Congenita Presentation in a Newborn With Pierpont Syndrome

Pierpont syndrome is a rare and recently described multiple congenital anomaly syndrome, classically characterized by global developmental delay, distinctive facial dysmorphic features, and abnormal fat distribution in distal limbs. Only few cases were previously documented. We report a case of a term male neonate admitted to the neonatal intensive care unit because of feeding difficulties. Intrauterine growth restriction, microcephaly, and bilateral equinovarus foot were diagnosed in the second trimester, and prenatal array comparative genomic hybridization showed no abnormality. Physical examination revealed bilateral flexion deformities of wrists, elbows, knees and clubfoot, large hands and feet, deep palmar and plantar grooves, and calcaneo-plantar fat pads. Craniofacial dysmorphism, axial hypotonia, and hypoactivity were also observed. Due to the presence of congenital and non-progressive joint contractures, arthrogryposis multiplex congenita (AMC) was considered. A comprehensive diagnostic workup, including a Next Generation Sequencing target panel, was performed but did not establish a diagnosis. The clinical exome identified an heterozygous pathogenic variant in the TBL1XR1 gene (NM_001321194.1: c.1337A>G, p.[Tyr446Cys]), allowing Pierpont syndrome diagnosis. Our case stands out for reporting the novel AMC presentation in a Pierpont syndrome newborn. The broader and precocious genetic testing proved to be an essential clarifying diagnostic tool. Our patient supports the relation between the p.Tyr446Cys sequence variant in TBL1XR1 gene with this rare syndrome, reinforcing its association with a distinctive and recognizable phenotype, as well as expanding its clinical features to include AMC.

Combining Gene Mutation with Expression of Candidate Genes to Improve Diagnosis of Escobar Syndrome

Escobar syndrome is a rare, autosomal recessive disorder that affects the musculoskeletal system and the skin. Mutations in the CHRNG and TPM2 genes are associated with this pathology. In this study, we conducted a clinical and genetic investigation of five patients and also explored via in silico and gene expression analysis their phenotypic variability. In detail, we identified a patient with a novel composite heterozygous variant of the CHRNG gene and two recurrent mutations in both CHRNG and TPM2 in the rest of the patients. As for the clinical particularities, we reported a list of modifier genes in a patient suffering from myopathy. Moreover, we identified decreased expression of IGF-1, which could be related to the short stature of Escobar patients, and increased expression of POLG1 specific to patients with TPM2 mutation. Through this study, we identified the genetic spectrum of Escobar syndrome in the Tunisian population, which will allow setting up genetic counseling and prenatal diagnosis for families at risk. In addition, we highlighted relevant biomarkers that could differentiate between patients with different genetic defects.