Mimicking TGFBI Hot-Spot Mutation Did Not Result in Any Deposit Formation in the Zebrafish Cornea.

PURPOSE: Mutations in transforming growth factor beta-induced (TGFBI) protein are associated with a group of corneal dystrophies (CDs), classified as TGFBI-associated CDs, characterized by deposits in the cornea. Mouse models were not proper in several aspects for modelling human disease. The goal of this study was to generate zebrafish mutants to investigate the corneal phenotype and to decide whether zebrafish could be a potential model for TGFBI-associated CDs. METHODS: The conserved arginine residue, codon 117, in zebrafish tgfbi gene was targeted with Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 method. Cas9 VQR variant was used with two target-specific sgRNAs to generate mutations. The presence of mutations was evaluated by T7 Endonuclease Enzyme (T7EI) assay and the type of the mutations were evaluated by Sanger sequencing. The mutant zebrafish at 3 months and 1 year of age were investigated under the microscope for corneal opacity and eye sections were evaluated histopathologically with hematoxylin-eosin, masson-trichrome and congo red stains for corneal deposits. RESULTS: We achieved indel variation at the target sequence that resulted in p.Ser115_Arg117delinsLeu (c. 347_353delinsT) by nonhomology mediated repair in F1. This zebrafish mutation had the potential to mimic two disease-causing mutations reported in human cases previously: R124L and R124L + del125-126. Mutant zebrafish did not show any corneal opacity or corneal deposits at 3 months and 1 year of age. CONCLUSION: This study generated the first zebrafish model mimicking the R124 hot spot mutation in TGFBI-associated CDs. However, evaluations even at 1 year of age did not reveal any deposits in the cornea histopathologically. This study increased the cautions for modelling TGFBI-associated CDs in zebrafish in addition to differences in the corneal structure between zebrafish and humans.

Six Years Follow-Up of an 11-Year-Old Girl with Anti-HMGCR Myopathy.

Anti-HMGCR myopathy is decribed as an immune-mediated necrotizing myopathy which is characterised by subacute, progressive proximal muscle weakness and elevated creatine kinase (CK) level. In pediatric population, anti-HMGCR myopathy has been reported solely as small case reports, albeit rare. Although treatment consensus has not yet been established, proper treatment with several immunomodulators to include IVIg can show remarkable improvement. We report an 11-year-old-girl diagnosed with anti-HMGCR myopathy with 6 years of follow-up.

Further expanding the phenotype of anti-Ku antibody associated disease in children and adolescents.

Anti-Ku autoantibodies are associated with several autoimmune inflammatory diseases. We aimed to review our anti-Ku positive pediatric patients in this study. Four pediatric patients (all female) who had anti-Ku positivity were included (Patients 1-2-3 with idiopathic inflammatory myopathy (IIM); Patient 4 with chronic urticaria). Patient 1 (onset:10.5 years) had proximal muscle weakness, Raynaud phenomenon, sclerodactyly, hyperpigmentation, joint contracture, and tenosynovitis. The disease course was progressive despite treatment with corticosteroids, intravenous immunoglobulin (IVIG), plasma exchange, and 11 different immunosuppressive drugs. Patient 2 (onset:15 years) presented with proximal muscle weakness, fatigue, weight loss. She recovered normal muscle strength after treatment with corticosteroids, IVIG, methotrexate, cyclosporine A, mycophenolate mofetil. Patient 3 (onset:10 years) had juvenile dermatomyositis with proximal muscle weakness, Gottron's papules, and calcinosis. She also had anti-NXP2 positivity. Remission was achieved with corticosteroids, methotrexate, azathioprine, and infliximab. Muscle biopsy findings revealed a variable spectrum of necrosis, regeneration, perifascicular pattern, and inflammation. Patient 4 had only chronic urticaria (onset: 6.5 years). The striking features of this series were heterogeneity in clinical presentations including solely chronic urticaria and IIM; variable response to immunosuppressive treatments; and histopathology revealing a spectrum of necrosis, regeneration and inflammatory infiltration. Expanding the spectrum of anti-Ku positivity will allow better understanding of anti-Ku-associated phenotype clusters.

Miopatía nemalínica tratada con L-tirosina para aliviar los síntomas en un recién nacido / Nemaline rod myopathy treated with L-tyrosine to relieve symptoms in a neonate

La miopatía nemalínica es un trastorno heterogéneo definido por la presencia de estructuras con forma de bastones, conocidas como cuerpos nemalínicos (o bastones de nemalina). El diagnóstico se funda en la debilidad muscular, además de la visualización de cuerpos nemalínicos en la biopsia muscular. La miopatía nemalínica no tiene cura. Las estrategias terapéuticas para este trastorno son sintomáticas y empíricas. En este artículo, presentamos el caso de una recién nacida con insuficiencia respiratoria grave y debilidad muscular generalizada, a la que se le diagnosticó miopatía nemalínica a través de la biopsia muscular. La paciente tuvo una notable disminución de la sialorrea y una mejora de los movimientos espontáneos después del tratamiento con L-tirosina. Este caso se presenta para destacar la importancia de la biopsia muscular en el diagnóstico diferencial de la hipotonía grave durante el período neonatal y el posible beneficio del aporte suplementario de L-tirosina para disminuir la sialorrea y restaurar la fuerza muscular.

Nemaline myopathy (NM) is a heterogeneous disorder defined by the presence of rod-shaped structures known as nemaline bodies or rods. The diagnosis is based on muscle weakness, combined with visualization of nemaline bodies on muscle biopsy. There is no curative treatment for nemaline myopathy. Therapeutic strategies for this condition are symptomatic and empirical. Herein, we present a newborn with severe respiratory failure and generalized muscle weakness, who was diagnosed as NM by muscle biopsy. The patient experienced remarkable decrease in sialorrhea and improvement of spontaneous movements after L-tyrosine treatment. This case is presented to emphasize the importance of muscle biopsy in the differential diagnosis of severe hypotonia during neonatal period and a possible benefit of L-tyrosine supplementation for decreasing sialorrhea and restoring muscle strength.