Is webbing (pterygia) a constant feature in patients with Escobar syndrome?

Comparative analysis of surgical treatment modalities for a popliteal pterygium: a meta-analysis

INTRODUCTION

Popliteal pterygium syndrome is a rare congenital disorder characterized by orofacial, cutaneous, musculoskeletal, and genital anomalies. The popliteal pterygium (PP) affects ambulation due to severe knee flexion contracture and equinovarus deformities. Surgical treatment aims to correct these deformities while preserving limb sensibility. However, due to its rarity, surgical guidelines are lacking.

MATERIALS AND METHODS

A meta-analysis according to PRISMA guidelines was conducted to summarize and compare surgical methods for PP. 183 paper were identified in PubMed and data from 32 articles were analyzed, including patient demographics, treatment modalities (Ilizarov fixator, femoral osteotomy, skin/soft tissue procedures, hamstring release, nerve surgery, and amputation), pre- and post-operative abilities to walk, knee joint parameters, complications, and recurrent contractions.

RESULTS

Among 58 patients (87 limbs), Ilizarov fixator demonstrated improved knee and ankle mobility postoperatively, but showed a relatively high surgical session count and complication rates. Femoral osteotomy achieved successful knee posture correction with fewer sessions and no complications. Isolated skin/soft tissue procedures improved flexion contracture and mobility, though they required several procedures. Hamstring release achieved notable contracture reduction but also necessitated multiple interventions. Nerve surgery and amputation had limited data, warranting further investigation.

CONCLUSION

The management of PP demands a comprehensive approach, considering individual patient characteristics and treatment outcomes. While different surgical modalities offer distinct benefits, a classification or guideline to treat this deformity is still lacking. Further research is essential to validate findings, refine treatment approaches, and enhance the quality of life for individuals with PP.

Arthrogryposis is a descriptive term, not a specific disease entity: Escobar Syndrome is an example

BACKGROUND

Children born with multiple congenital contractures have been almost always given the diagnosis of arthrogryposis multiplex congenita. Arthrogryposis is a descriptive term, not a specific disease entity. A heterogeneous group of conditions associated with multiple congenital joint contractures (mostly syndromic) should be considered.

METHODS

The records of seven children (four boys and three girls aged 6 months - 11 years) of different ethnic origins have been included in this study. The constellation of specific craniofacial dysmorphic features, spine malformation complex, and appendicular skeletal abnormalities in addition to camptodactyly, talipes equinovarus and rocker-bottom feet were a cluster of malformation complex encountered in our patients. Via comprehensive clinical and imaging study (3D reconstruction CT scan), definite diagnosis of Escobar Syndrome has been approached.

RESULTS

The clinical and imaging phenotype was the key factor towards etiological understanding, treatment and genotype confirmation. We identified compound heterozygous mutations (c.459dupA [p.Val154Serfs*24] and c.794T>G [p.Leu265Serfs*24] of the CHRNG gene in four patients. Bilateral flexion contractures of the knees have been treated by using Iliazarov external fixator. Simultaneous corrections of scoliosis have been achieved by applying either dual traditional growing rods or single growing rods.

CONCLUSIONS

The clinical and radiological phenotypic characterizations are the fundamental tool in differentiating Escobar from other forms of multiple contractures. The aim of this study are three folds, firstly to demonstrate the importance of detecting the etiological understanding in children presented with multiple contractures, secondly to refute the general conception among the vast majority of pediatricians and orthopedic surgeons that arthrogryposis multiplex is a diagnostic entity. And thirdly, we were able to detect severe spine deformity via 3D reconstruction CT scan, namely unsegmented posterior spinal bar.

Case report: Exome sequencing revealed disease-causing variants in a patient with spondylospinal thoracic dysostosis

Background

Spondylocostal dysostosis is a rare genetic disorder caused by mutations in DLL3, MESP2, LFNG, HES7, TBX6, and RIPPLY2. A particular form of this disorder characterized by the association of spondylocostal dysostosis with multiple pterygia has been reported and called spondylospinal thoracic dysostosis. Both disorders affect the spine and ribs, leading to abnormal development of the spine. Spondylospinal thoracic dysostosis is a rare syndrome characterized by the association of multiple vertebral segmentation defects, thoracic cage deformity, and multiple pterygia. This syndrome can be considered a different form of the described spondylocostal dysostosis. However, no genetic testing has been conducted for this rare disorder so far.

Methods

We report here the case of an 18-month-old female patient presenting the clinical and radiological features of spondylospinal thoracic dysostosis. To determine the underlying genetic etiology, whole exome sequencing (WES) and Sanger sequencing were performed.

Results

Using WES, we identified a variant in the TPM2 gene c. 628C>T, already reported in the non-lethal form of multiple pterygium syndrome. In addition, following the analysis of WES data, using bioinformatic tools, for oligogenic diseases, we identified candidate modifier genes, CAP2 and ADCY6, that could impact the clinical manifestations.

Conclusion

We showed a potential association between TPM2 and the uncommon spondylocostal dysostosis phenotype that would require further validation on larger cohort.

Clinical and Pathologic Features of Congenital Myasthenic Syndromes Caused by 35 Genes-A Comprehensive Review

Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS (AGRN, ALG14, ALG2, CHAT, CHD8, CHRNA1, CHRNB1, CHRND, CHRNE, CHRNG, COL13A1, COLQ, DOK7, DPAGT1, GFPT1, GMPPB, LAMA5, LAMB2, LRP4, MUSK, MYO9A, PLEC, PREPL, PURA, RAPSN, RPH3A, SCN4A, SLC18A3, SLC25A1, SLC5A7, SNAP25, SYT2, TOR1AIP1, UNC13A, VAMP1). The 35 genes can be classified into 14 groups according to the pathomechanical, clinical, and therapeutic features of CMS patients. Measurement of compound muscle action potentials elicited by repetitive nerve stimulation is required to diagnose CMS. Clinical and electrophysiological features are not sufficient to identify a defective molecule, and genetic studies are always required for accurate diagnosis. From a pharmacological point of view, cholinesterase inhibitors are effective in most groups of CMS, but are contraindicated in some groups of CMS. Similarly, ephedrine, salbutamol (albuterol), amifampridine are effective in most but not all groups of CMS. This review extensively covers pathomechanical and clinical features of CMS by citing 442 relevant articles.

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.

CHRNG-related nonlethal multiple pterygium syndrome: Muscle imaging pattern and clinical, histopathological, and molecular genetic findings

Mutations in the CHRNG gene cause autosomal recessive multiple pterygium syndrome (MPS). Herein we present a long-term follow-up of seven patients with CHRNG-related nonlethal MPS and we compare them with the 57 previously published patients. The objective is defining not only the clinical, histopathological, and molecular genetic characteristics, but also the type and degree of muscle involvement on whole-body magnetic resonance imaging (WBMRI). CHRNG mutations lead to a distinctive phenotype characterized by multiple congenital contractures, pterygium, and facial dysmorphism, with a stable clinical course over the years. Postnatal abnormalities at the neuromuscular junction were observed in the muscle biopsy of these patients. WBMRI showed distinctive features different from other arthrogryposis multiple congenita. A marked muscle bulk reduction is the predominant finding, mostly affecting the spinal erector muscles and gluteus maximus. Fatty infiltration was only observed in deep paravertebral muscles and distal lower limbs. Mutations in CHRNG are mainly located at the extracellular domain of the protein. Our study contributes to further define the phenotypic spectrum of CHRNG-related nonlethal MPS, including muscle imaging features, which may be useful in distinguishing it from other diffuse arthrogryposis entities.