Exon skipping is a promising strategy for Duchenne muscular dystrophy (DMD) disease-modifying therapy. To make this approach safe, ensuring that excluding one or more exons will restore the reading frame and that the resulting protein will retain critical functions of the full-length dystrophin protein is necessary. However, in vivo testing of the consequences of skipping exons that encode the N-terminal actin-binding domain (ABD) has been confounded by the absence of a relevant animal model. We created a mouse model of the disease recapitulating a novel human mutation, a large de novo deletion of exons 8-34 of the DMD gene, found in a Russian DMD patient. This mutation was achieved by deleting exons 8-34 of the X-linked mouse Dmd gene using CRISPR/Cas9 genome editing, which led to a reading frame shift and the absence of functional dystrophin production. Male mice carrying this deletion display several important signs of muscular dystrophy, including a gradual age-dependent decrease in muscle strength, increased creatine kinase, muscle fibrosis and central nucleation. The degrees of these changes are comparable to those observed in mdx mice, a standard laboratory model of DMD. This new model of DMD will be useful for validating therapies based on skipping exons that encode the N-terminal ABD and for improving our understanding of the role of the N-terminal domain and central rod domain in the biological function of dystrophin. Simultaneous skipping of exons 6 and 7 should restore the gene reading frame and lead to the production of a protein that might retain functionality despite the partial deletion of the ABD.

5q spinal muscular atrophy (5q SMA) is one of the most common autosomal recessive disorders in the Russian Federation. The first medication to treat 5q SMA was registered in the Russian Federation for treatment of all 5q SMA types in 2019, and the last of the three currently available in December 2021. We launched the pilot newborn screening (NBS) program for 5q SMA in Moscow, the Russian Federation, starting in 2019. During the pilot program, 23,405 neonates were tested for the deletion of exon 7 of the SMN1 gene, the most common cause of 5q SMA. We used the SALSA^® MC002 SMA Newborn Screen Kit (MRC Holland) to specifically detect homozygous deletions of SMN1 exon 7. We used the restriction fragment length polymorphism (RFLP) approach to validate detected homozygous deletions and the SALSA MLPA Probemix P060 SMA Carrier Kit (MRC Holland) to determine the SMN2 exon 7 copy number to prescribe gene therapy for 5q SMA. Three newborns with a homozygous deletion of the SMN1 gene were detected. The calculated birth prevalence of 1:7801 appears to be similar to the results in other European countries. The children did not show any signs of respiratory involvement or bulbar weakness immediately after birth. Until now, no 5q SMA case missed by NBS has been detected.

Objective: to analyze the safety and evaluate the effectiveness of therapy with onasemnogene abeparvovec in patients with spinal muscular atrophy in real clinical practice based on the experience of using the drug in the neuromuscular center of Research Clinical Pediatric Institute of Pirogov Russian National Research Medical University.Materials and methods. Patients with spinal muscular atrophy received therapy with onasemnogene abeparvovec based on the prescription of the drug according to vital indications by a council of physicians of Federal institutions (the availability of the drug was carried out within the framework of the MAP Program (global program of managed access MAP to AVXS-101 for eligible patients in countries, where it is not approved by regulatory authorities (NCT03955679), through funding from the charitable foundations, as well as through funding from the state fund “Circle of Kindness”. The drug tolerance was assessed and the analysis of side effects after drug administration was based on the criteria for adverse events (General criteria Adverse Event Terminology (CTCAE) v. 5.0) Patient motor function was assessed prior to treatment initiation and every 3–6 months after therapy using the Philadelphia Pediatric Hospital’s CHOP INTEND scale, total motor development based on Hammersmith Hospital Neurological Assessment Scale in Young Children, Part 2 (HINE-2), and the acquisition of new motor skills.Results. 41 children aged 5 to 47 months (weighing no more than 21 kg) received therapy with onasemnogene abeparvovec in the period from April 2020 to December 2021. Adverse events (hyperthermia, decreased appetite, nausea, vomiting) were registered in all patients with different degree of severity. Elevated levels of transaminases greater than 2 times the upper limit of the normal range were observed in 32 patients (78 %), thrombocytopenia in 9 patients (22 %). 15 patients (36 %) required a dose adjustment of corticosteroids.17 patients underwent assessment of motor scales after 6 months, 10 children were assessed after a year. The average improvement on the HINE-2 scale was 3.3 / 4.4 points, respectively. The average improvement on the CHOP INTEND Scale was 7.1 / 9.4 points after 6 / 12 months of therapy.Conclusion. The efficacy and safety of onasemnogene abeparvovec have been demonstrated in real clinical practice in the treatment of spinal muscular atrophy for children in different age groups with a body weight of no more than 21 kg.

Introduction. Spinal muscular atrophy is a severe neuromuscular disease characterized by rapid progression of muscle weakness and early death. Pathogenetic therapy with nusinersen can significantly change the course of the disease and enable the patient to acquire new skills. The study of the efficacy and safety of nusinersen therapy in patients with type 1 spinal muscular atrophy should be continued. The aim of the study was to assess the safety and efficacy of nusinersen therapy in patients with type 1 spinal muscular atrophy for 6 months as part of an expanded access program at federal and regional healthcare facilities. Materials and methods. Patients with type 1 spinal muscular atrophy received nusinersen therapy under the expanded access program (NCT02865109). Patients were evaluated before starting treatment and 6 months after starting treatment. Overall motor development and motor function was assessed using the Hammersmith Infant Neurological Status Scale Part 2 and the Philadelphia Pediatric Hospital Neonatal Motor Scale. Results. 41 children aged 6 to 38 months received nusinersen therapy between July 2019 and March 2020. At the time of analysis, all patients were alive and continued treatment. The average improvement on the Hammersmith Hospital Neurological Status Scale was 3.7 points after 6 months of therapy compared to baseline (n = 39, p 0.001). The mean improvement on the Children’s Hospital of Philadelphia Scale for the Diagnosis of Motor Function in Newborns was 9.8 after 6 months of therapy from baseline (n = 30, p 0.001). Conclusion. The efficacy and safety of nusinersen have been demonstrated in real clinical practice in Russia in the treatment of early-onset spinal muscular atrophy.

Гены туберозного склероза (TSC1 и TSC2) в норме функционируют как классические гены-супрессоры опухолевого роста; потеря функции этих генов приводит к активации киназы mTOR и развитию доброкачественных опухолей. Несмотря на медленное прогрессирование, субэпендимальные гигантоклеточные астроцитомы и ангиомиолипомы почек могут вызывать летальные исходы. Ингибитор mTOR эверолимус продемонстрировал хорошую эффективность и переносимость как в I–II, так и в III фазе исследований (EXIST-1 и EXIST-2): уменьшение объема астроцитом на 50% и более — у 35% пациентов, объема ангиомиолипом на 50% и более — у 41,8%. Через 3,5 года исследований эверолимус демонстрировал высокий процент удержания на препарате — 80,2 и 79% соответственно. Побочные эффекты отмечались практически у всех пациентов, наиболее часто наблюдались стоматиты, язвы слизистой рта, назофарингит. Эверолимус был зарегистрирован в РФ, и рос- сийские пациенты принимали участие в международных исследованиях EXIST-1 и EXIST-2. Показания для назначения препарата при туберозном склерозе — субэпендимальные гигантоклеточные астроцитомы у пациентов старше 3 лет и ангиомиолипомы у пациентов старше 18 лет, ассоциированные с туберозным склерозом. Эверолимус обладает потенциалом таргетного воздействия на спектр клинических проявлений туберозного склероза.

The social-economic burden of spinal muscular atrophy in Russia