The distal arthrogryposis-linked p.R63C variant promotes the stability and nuclear accumulation of TNNT3.

BACKGROUND: Distal arthrogryposis (DA) is comprised of a group of rare developmental disorders in muscle, characterized by multiple congenital contractures of the distal limbs. Fast skeletal muscle troponin-T (TNNT3) protein is abundantly expressed in skeletal muscle and plays an important role in DA. Missense variants in TNNT3 are associated with DA, but few studies have fully clarified its pathogenic role. METHODS: Sanger sequencing was performed in three generation of a Chinese family with DA. To determine how the p.R63C variant contributed to DA, we identified a variant in TNNT3 (NM_006757.4): c.187C>T (p.R63C). And then we investigated the effects of the arginine to cysteine substitution on the distribution pattern and the half-life of TNNT3 protein. RESULTS: The protein levels of TNNT3 in affected family members were 0.8-fold higher than that without the disorder. TNNT3 protein could be degraded by the ubiquitin-proteasome complex, and the p.R63C variant did not change TNNT3 nuclear localization, but significantly prolonged its half-life from 2.5 to 7 h, to promote its accumulation in the nucleus. CONCLUSION: The p.R63C variant increased the stability of TNNT3 and promoted nuclear accumulation, which suggested its role in DA.

De novo mutations of SCN1A are responsible for arthrogryposis broadening the SCN1A-related phenotypes.

BACKGROUND: Arthrogryposis multiplex congenita (AMC) is the direct consequence of reduced fetal movements. AMC includes a large spectrum of diseases which result from variants in genes encoding components required for the formation or the function of the neuromuscular system. AMC may also result from central nervous involvement. SCN1A encodes Nav1.1, a critical component of voltage-dependent sodium channels which underlie action potential generation and propagation. Variants of SCN1A are known to be responsible for Dravet syndrome, a severe early-onset epileptic encephalopathy. We report pathogenic heterozygous missense de novo variants in SCN1A in three unrelated individuals with AMC. METHODS: Whole-exome sequencing was performed from DNA of the index case of AMC families. Heterozygous missense variants in SCN1A (p.Leu893Phe, p.Ala989Thr, p.Ile236Thr) were identified in three patients. Sanger sequencing confirmed the variants and showed that they occurred de novo. RESULTS: AMC was diagnosed from the second trimester of pregnancy in the three patients. One of them developed drug-resistant epileptic seizures from birth. We showed that SCN1A is expressed in both brain and spinal cord but not in skeletal muscle during human development. The lack of motor denervation as established by electromyographic studies or pathological examination of the spinal cord or skeletal muscle in the affected individuals suggests that AMC is caused by brain involvement. CONCLUSION: We show for the first time that SCN1A variants are responsible for early-onset motor defect leading to AMC indicating a critical role of SCN1A in prenatal motor development and broadening the phenotypic spectrum of variants in SCN1A.

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.

Association Between Arthrogryposis and Mortality in Infants With Congenital Zika Syndrome: A Systematic Review and Meta-analysis.

BACKGROUND: Intrauterine Zika virus infection is associated with neurological disorders and other problems, including such as impaired visual and hearing function and orthopedic abnormalities, including arthrogryposis. We systematically investigated the prevalence of arthrogryposis in infants with congenital Zika syndrome and the respective risk of mortality. METHODS: We conducted a systematic review and meta-analysis of reports published in PubMed, Web of Science, SCOPUS, and World Health Organization Global Index Medicus databases, using the keywords Zika virus and arthrogryposis and related terms. RESULTS: After screening titles and abstracts, a total of four studies were included. Arthrogryposis was not associated with increased risk for fetal demise (risk ratio, 3.33; 95% confidence interval, 0.73 to 15.26). However, arthrogryposis was associated with a 13-fold increased risk of mortality in neonates with congenital Zika syndrome (risk ratio, 13.11; 95% confidence interval, 3.74 to 45.92) than neonates with congenital Zika syndrome but without arthrogryposis. CONCLUSIONS: Neonates with both congenital Zika syndrome and arthrogryposis had higher morbidity and mortality risks, making it necessary to implement protocols for the early identification of neuromuscular changes and appropriate management of patients.

Arthrogryposis Multiplex Congenita.

Arthrogryposis multiplex congenita (AMC) is a complex, etiologically diverse, clinical descriptor identified in a variety of diagnoses characterized by multiple congenital joint contractures. The root cause of AMC is decreased fetal movement in-utero, whether resulting from maternal or pregnancy influences, nervous system pathology, or an underlying genetic abnormality. Prenatal diagnosis via ultrasonography can be challenging and may require additional imaging techniques or studies. After birth, these infants may require assistance breathing and feeding depending on the underlying diagnosis. Physical therapy and surgical intervention of the contractures are the mainstays of therapy, and outcomes can be good when intervention is provided in a timely manner. Those infants with syndromic causes of arthrogryposis are more likely to have poor outcomes; therefore, determining the underlying etiology for AMC is important as this can influence counseling regarding individual prognosis as well as future pregnancies. [Pediatr Ann. 2020;49(7):e299-e304.].

Myasthaenia gravis in pregnancy, delivery and newborn.

INTRODUCTION: Myasthaenia gravis (MG) is the most common disease of the neuromuscular junction; clinical presentation of the disease includes a variety of symptoms, the most frequent beign the only ocular muscles involvement, to the generalized myasthenic crisis with diaphragmatic impairment and respiratory insufficiency. It is most common in women between 20 ad 40 years. EVIDENCE ACQUISITION: We performed a comprehensive search of relevant studies from January1990 to Dicember 2019 to ensure all possible studies were captured. A systematic search of Pubmed databases was conducted. EVIDENCE SYNTHESIS: Pregnancy has an unpredictable and variable effect on the clinical course of MG; however, a stable disease before is likely not to relapse during pregnancy. exacerbations can still occur more often during the first trimester and the post partum period. The transplacental passage of antibodies results in a neonatal transient disease, whereas the major concern is related to foetal malformations such as fetal arthrogryposis and polyhydramnios. The overall neonatal outcome described in literature is variable, perinatal mortality in women with MG is generally the same as non affected patients, although in one study the risk of premature rupture of the membranes was higher. Treatment of MG in pregnangncy includes pyridostigmine and corticosteroids, although the latter have been associated with higher risk of cleft palate, premature rupture of the membranes and preterm delivery. These drugs appear also to be safe in breastfeeding. In MG patients spontaneous vaginal delivery should be encouraged, for surgery could cause acute worsening of myasthenic symptoms; also an accurate anesthesiological evaluation must be performed prior to both general and local anesthesia due to increased risk of complications. CONCLUSIONS: Most of the myasthenic women could have uneventful pregnancy with good obstetrical outcomes, both for mother and neonate. However, a careful planning of pregnancy and multidisciplinary team approach, composed by neurologists, obstetricians, neonatologists and anesthesiologists, is required to manage these pregnancies.

X-linked infantile spinal muscular atrophy (SMAX2) caused by novel c.1681G>A substitution in the UBA1 gene, expanding the phenotype.

X-linked infantile spinal muscular atrophy (SMAX2), OMIM 301830, is a rare, severe form of spinal muscular atrophy, caused by variants in the Ubiquitin like modifier-activating enzyme 1 (UBA1) gene. Clinical features reported to date include marked hypotonia, areflexia, arthrogryposis, contractures, myopathic facies and tongue fibrillations. Previous reports have included a history of contractures. We report a male patient presenting following a normal pregnancy with typical symptoms of X-linked infantile spinal muscular atrophy including hypotonia, weakness, areflexia and respiratory insufficiency, however contractures were absent. There was a significant family history of neuromuscular disease on the maternal side, with several male relatives all dying before the age of six months. Creatine Kinase was mildly elevated, MRI Brain was normal and neurophysiological testing revealed a diffuse motor neuronopathy. Genetic testing for SMN1 gene was normal. UBA1 sequencing revealed a maternally inherited hemizygous familial variant [c.1681G>A p. (Asp561Asn)], which has not been previously reported.

Lipomas of the Brachial Plexus: A Case Series and Review of the Literature.

BACKGROUND: Lipomas are common benign tumors. When they develop in proximity to peripheral nerves, they can cause neurologic symptoms secondary to mass effect. Previous reports have shown symptom resolution after removal of lipomas compressing various upper extremity peripheral nerves. However, brachial plexus lipomas are relatively rare. Our multidisciplinary experience with brachial plexus lipoma resection is reviewed in the largest case series to date. METHODS: A retrospective chart review of all patients undergoing resection of brachial plexus lipomatous tumors between 2006 and 2016 was performed. Patient demographic data, diagnostic imaging, clinical presentation, operative details, surgical pathology, and clinical outcomes were reviewed. RESULTS: Twelve brachial plexus lipomatous tumors were resected in 11 patients: 10 lipomas, 1 hibernoma, and 1 atypical lipomatous tumor. The most common tumor location was supraclavicular (50%), followed by axillary (42%), and proximal medial arm (8%). The most common brachial plexus segment involved was the upper trunk (50%), followed by posterior cord (25%), lateral pectoral nerve (8%), lower trunk (8%), and proximal median nerve (8%). Most patients presented with an enlarging painless mass (58%). Of the patients who presented with neurologic symptoms, symptoms resolved in the majority (80%). CONCLUSIONS: Brachial plexus lipomas are rare causes of compression neuropathy in the upper extremity. Careful resection and knowledge of brachial plexus anatomy, which may be distorted by the tumor, are critical to achieving a successful surgical outcome with predictable symptom resolution. Finally, surveillance magnetic resonance imaging may be warranted for atypical lesions.

Development of a research platform for children with arthrogryposis multiplex congenita: study protocol for a pilot registry.

INTRODUCTION: Arthrogryposis multiplex congenita (AMC) describes a heterogeneous group of conditions with multiple congenital contractures. These conditions may be attributed to genetic or other factors inducing decreased fetal movements, including maternal and paternal factors. Discovering the underlying genetic pathways has important repercussions for prevention, gene therapy and genetic counselling. The current literature mainly consists of small-scale, single-site studies, limiting comparability and pooling of findings across individual studies. A pilot registry for children presenting with AMC is proposed to provide the framework for a large-scale AMC registry. This registry will provide the platform to support high-quality studies to inform the distribution, clinical practice and genetics contributing to this group of conditions. METHODS AND ANALYSIS: The registry will be piloted on 40 families of children from birth to 21 years of age presenting with AMC. Data will be collected on the child (demographic and newborn variables), mother and father (demographic, lifestyle habits and medical history). To promote standardised data collection, a manual of operations will be developed. Descriptive statistics will be used to summarise relevant data, regression analyses will be used to explore associations to generate hypotheses regarding factors contributing to AMC. Qualitative analysis will also be used to better describe the various phenotypes. ETHICS AND DISSEMINATION: Ethics approval was obtained at the participating sites. The pilot registry will provide the platform for multisite AMC registry that will generate multiple research avenues to enhance current care and establish new therapies. Following this pilot study, the participant selection criteria will be refined and datasets will be expanded to include rehabilitation and surgical interventions, and genetic sequencing. The best timing for the questionnaire administration and frequency of follow-up prior to the implementation of a multisite AMC registry will be determined.

Compression neuropathy of common peroneal nerve caused by a popliteal cyst: A case report.

RATIONALE: Popliteal cyst developing in the sheath of a peripheral nerve or joint capsule may cause compression neuropathy. Although popliteal cyst is very common lesion, it seldom causes serious complications. Common peroneal nerve compression is rarely caused by an extraneural popliteal cyst. PATIENT CONCERNS: We presented the case of a 52-year-old female with common peroneal nerve compression caused by an extraneural popliteal cyst. DIAGNOSES: Electromyography showed the damage of common peroneal nerve. MRI magnetic resonance imaging showed the lump to be a popliteal cyst. She was diagnosed as peroneal nerve injury and popliteal cyst. INTERVENTIONS: The patient was performed peroneal nerve decompression and popliteal cyst excision surgery. We excised the cyst completely and soluted the common peroneal nerve thoroughly. The cyst was filled with thick mucinous material. OUTCOMES: The pathological report showed that the excised mass was a popliteal cyst. There were no postoperative complications. Pain and hypoesthesia resolved 6 months after surgery. LESSONS: In this case, compression of the common peroneal nerve was due to an extraneural popliteal cyst, a situation rarely encountered. MRI can show in better detail their size and internal contents as well as their relation with surrounding anatomic structures. Patients with nerve entrapment caused by enlarged or ruptured cysts must be microsurgically excised if symptomatic.

A novel ECEL1 mutation expands the phenotype of distal arthrogryposis multiplex congenita type 5D to include pretibial vertical skin creases.

Arthrogryposis multiplex congenita (AMC) is a heterogeneous disorder characterized by multiple joint contractures often in association with other congenital abnormalities. Pretibial linear vertical creases are a rare finding associated with arthrogryposis, and the etiology of the specific condition is unknown. We aimed to genetically and clinically characterize a boy from a consanguineous family, presenting with AMC and pretibial vertical linear creases on the shins. Whole exome sequencing and variant analysis revealed homozygous novel missense variants of ECEL1 (c.1163T > C, p.Leu388Pro, NM_004826) and MUSK (c.2572C > T, p.Arg858Cys, NM_005592). Both variants are predicted to have deleterious effects on the protein function, with amino acid positions highly conserved among species. The variants segregated in the family, with healthy mother, father, and sister being heterozygous carriers and the index patient being homozygous for both mutations. We report on a unique patient with a novel ECEL1 homozygous mutation, expanding the phenotypic spectrum of Distal AMC Type 5D to include vertical linear skin creases. The homozygous mutation in MUSK is of unknown clinical significance. MUSK mutations have previously shown to cause congenital myasthenic syndrome, a neuromuscular disorder with defects in the neuromuscular junction.

Miopatía de depósito de nemalina y artrogriposis congénita / Nemaline myopathy and congenital arthrogryposis

La artrogriposis es un síndrome complejo, que responde etiológicamente a numerosas causas congénitas y adquiridas. Presentamos un caso familiar de artrogriposis. La necropsia aportó el hallazgo de inclusiones rojo-púrpura en el sarcoplasma del tejido muscular, sugestiva de miopatía por nemalinas

Arthrogryposis is a complex syndrome, the aetiology of which can be traced to numerous congenital and acquired causes. We present a case of familiar arthrogryposis. Necropsy revealed red-purple rod-like structures in the sarcoplasm of the muscle tissue, suggestive of nemaline myopathy

Spectrum of Spinal Cord, Spinal Root, and Brain MRI Abnormalities in Congenital Zika Syndrome with and without Arthrogryposis.

BACKGROUND AND PURPOSE: Arthrogryposis is among the malformations of congenital Zika syndrome. Similar to the brain, there might exist a spectrum of spinal cord abnormalities. The purpose of this study was to explore and describe in detail the MR imaging features found in the spinal cords, nerve roots, and brains of children with congenital Zika syndrome with and without arthrogryposis. MATERIALS AND METHODS: Twelve infants with congenital Zika syndrome (4 with arthrogryposis and 8 without) who had undergone brain and spinal cord MR imaging were retrospectively selected. Qualitative and quantitative analyses were performed and compared between groups. RESULTS: At visual inspection, both groups showed reduced thoracic spinal cord thickness: 75% (6/8) of the group without arthrogryposis and 100% (4/4) of the arthrogryposis group. However, the latter had the entire spinal cord reduced and more severely reduced conus medullaris anterior roots (respectively, P = .002 and .007). Quantitative differences were found for conus medullaris base and cervical and lumbar intumescences diameters (respectively, P = .008, .048, .008), with more prominent reduction in arthrogryposis. Periventricular calcifications were more frequent in infants with arthrogryposis (P = .018). CONCLUSIONS: Most infants had some degree of spinal cord thickness reduction, predominant in the thoracic segment (without arthrogryposis) or in the entire spinal cord (with arthrogryposis). The conus medullaris anterior roots were reduced in both groups (thinner in arthrogryposis). A prominent anterior median fissure of the spinal cord was absent in infants without arthrogryposis. Brain stem hypoplasia was present in all infants with arthrogryposis, periventricular calcifications, in the majority, and polymicrogyria was absent.

α-granule biogenesis: from disease to discovery.

Platelets are critical to hemostasis and thrombosis. Upon detecting injury, platelets show a range of responses including the release of protein cargo from α-granules. This cargo is synthesized by platelet precursor megakaryocytes or endocytosed by megakaryocytes and/or platelets. Insights into α-granule biogenesis have come from studies of hereditary conditions where these granules are immature, deficient or absent. Studies of Arthrogryposis, Renal dysfunction, and Cholestasis (ARC) syndrome identified the first proteins essential to α-granule biogenesis: VPS33B and VPS16B. VPS33B and VPS16B form a complex, and in the absence of either, platelets lack α-granules and the granule-specific membrane protein P-selectin. Gray Platelet Syndrome (GPS) platelets also lack conventionally recognizable α-granules, although P-selectin containing structures are present. GPS arises from mutations affecting NBEAL2. The GPS phenotype is more benign than ARC syndrome, but it can cause life-threatening bleeding, progressive thrombocytopenia, and myelofibrosis. We review the essential roles of VPS33B, VPS16B, and NBEAL2 in α-granule development. We also examine the existing data on their mechanisms of action, where many details remain poorly understood. VPS33B and VPS16B are ubiquitously expressed and ARC syndrome is a multisystem disorder that causes lethality early in life. Thus, VPS33B and VPS16B are clearly involved in other processes besides α-granule biogenesis. Studies of their involvement in vesicular trafficking and protein interactions are reviewed to gain insights into their roles in α-granule formation. NBEAL2 mutations primarily affect megakaryocytes and platelets, and while little is known about NBEAL2 function some insights can be gained from studies of related proteins, such as LYST.

Microcephaly and arthrogryposis multiplex congenita: The full-blown CNS spectrum in newborns with ZIKV infection.

The recent alarming statements concerning the newborn ZIKV-induced microcephaly epidemics in the Northeast of Brazil, released by the Brazilian Ministry of Health, as well as important international health agencies, such as the World Health Organization and the Pan American Health Organization, raised many "why and how" questions so far, that will hopefully be scientifically answered, as more researches in that regard come up in the long term. In this paper, we describe another potentially ZIKV-induced central nervous system and musculoskeletal disorder that has accompanied microcephaly in these children: atrhogryposis multiplex congenita. The goal is to bring up some hypotheses for possible underlying molecular mechanisms based on published data taken from animal models, such as ovine and cattle, which once infected by other types of arboviroses and viruses that also belong to the Flaviviridae family, presented, too, with the full-blown CNS spectrum of malformations at birth.

Prevalence of thoracic spine lesions masquerading as cauda equina syndrome: yield of a novel magnetic resonance imaging protocol.

Our objective was to describe the yield of actionable thoracic spine lesions for a novel magnetic resonance imaging (MRI) protocol including evaluation of the thoracic spine among patients presenting to the Emergency Department (ED) with symptoms consistent with epidural compression syndrome. Our ED and Department of Radiology together designed a novel rapid MRI protocol entailing 3D volumetric T2 weighted sequences through both the thoracic and lumbar spine obtained in the sagittal plane to assess for both lumbar and thoracic spine lesions. We recorded study outcomes for all patients undergoing this protocol or conventional lumbar MRI during May 2014-May 2015 to determine the prevalence of actionable thoracic spine lesions. We defined an actionable thoracic lesion as any pathology requiring treatment (e.g., medication, admission, surgery) not otherwise indicated on the basis of lumbar spine findings. During the study period, 112 of 124 (90.3%) of ED patients undergoing MRI evaluation for epidural compression syndrome underwent the novel protocol. The remaining patients underwent evaluation of the lumbar spine using only a conventional MRI protocol. Of the 112 patients undergoing the novel protocol, 6 (5.4%) patients had thoracic spine lesions indicating therapy not otherwise indicated by lumbar spine findings. The etiologies of these six lesions were: neoplasms (2), de-myelination (2), compression fracture (1), and degeneration due to pernicious anemia (1). Emergency providers should strongly consider the routine use of MRI protocols including thoracic spine evaluation in patients presenting to the ED with symptoms consistent with epidural compression syndrome.

Type 0 Spinal Muscular Atrophy: Further Delineation of Prenatal and Postnatal Features in 16 Patients.

BACKGROUND: Spinal muscular atrophy (SMA) is caused by homozygous inactivation of the SMN1 gene. The SMN2 copy number modulates the severity of SMA. The 0SMN1/1SMN2 genotype, the most severe genotype compatible with life, is expected to be associated with the most severe form of the disease, called type 0 SMA, defined by prenatal onset. OBJECTIVE: The aim of the study was to review clinical features and prenatal manifestations in this rare SMA subtype. METHODS: SMA patients with the 0SMN1/1SMN2 genotype were retrospectively collected using the UMD-SMN1 France database. RESULTS: Data from 16 patients were reviewed. These 16 patients displayed type 0 SMA. At birth, a vast majority had profound hypotonia, severe muscle weakness, severe respiratory distress, and cranial nerves involvement (inability to suck/swallow, facial muscles weakness). They showed characteristics of fetal akinesia deformation sequence and congenital heart defects. Recurrent episodes of bradycardia were observed. Death occurred within the first month. At prenatal stage, decreased fetal movements were frequently reported, mostly only by mothers, in late stages of pregnancy; increased nuchal translucency was reported in about half of the cases; congenital heart defects, abnormal amniotic fluid volume, or joint contractures were occasionally reported. CONCLUSION: Despite a prenatal onset attested by severity at birth and signs of fetal akinesia deformation sequence, prenatal manifestations of type 0 SMA are not specific and not constant. As illustrated by the frequent association with congenital heart defects, type 0 SMA physiopathology is not restricted to motor neuron, highlighting that SMN function is critical for organogenesis.