Background. Onasemnogene abeparvovec is the first gene replacement therapy medication based on the adeno-associated viral vector (AAV9). One injection to a patient with 5q spinal muscular atrophy (SMA) leads to replacement of the missing or defective SMN1 gene with its functional copy. It leads to normalization of survival motor neuron protein (SMN) production.Objective. The aim of the study is to evaluate efficacy, safety, and causes of different responses to therapy after single administration of onasemnogene abeparvovec in 5 patients with 5q SMA (types I and II) comparing the baseline status with the results of continued monitoring in real clinical practice in Russian Federation.Methods. Interim results of continued follow-up of children with 5q SMA with 2–3 copies of the SMN2 gene are presented: 2 boys and 1 girl with type I who received single dose of onasemnogene abeparvovec at 4 and 7 months of age; and 2 girls with type II who received therapy at 11 and 16 months of age.Results. Short-term controlled fever was observed in 4 out of 5 patients during first 2 weeks after viral vector therapy administration (max in patient 5 — up to 38.5 ° C). All 5 children had transaminases increase, 1 patient — significant transaminases increase during the sensitisation period (> 10 from upper normal level (UNL)), 1 patient — delayed significant transaminases increase (> 20 UNL), 1 patient — transaminases increase (> 3 UNL) after discontinuation of longterm therapy with glucocorticosteroids (according to prescribing information). All patients had shown positive and sustained response to therapy over time at motor status assessment via CHOP INTEND / HFMSE scales. The more significant response was observed in patients with less aggressive baseline 5q SMA type II with 3 copies of the SMN2 gene.Conclusion. Onasemnogene abeparvovec is relatively safe medication for management of children with 5q SMA. Thus, the development of adverse events and their mechanisms should be further studied, as well as long-term follow-up of recipients is required to gather knowledge on this medication effects on human body.

Objective. To analyze the natural course of type 1 spinal muscular atrophy in children with the onset of the disease up to 6 months in the Russian population.Material and methods. The retrospective multicenter study included data of 54 children with an established diagnosis of type 1 spinal muscular atrophy who did not receive therapy with nusinersen, risdiplam, branaplam, onasemogen abeparvovec-xioi, or other anti-sense oligonucleotides / selective SMN2 splicing modifiers or genetherapy drugs for SMN1 genetransduction. Basedon medical records, the scientists have collected all available information on the health status of children, the need for respiratory support and death or start of long-term mechanical ventilation.Results. The median time from birth to the onset of the combined event (death or initiation of long-term respiratory support), determined using the Kaplan-Meier method, was 365 [269; 409] days (12 months). The date of death was known in 22 out of 54 children. The median age of death was 301,5 [181; 375] days (9,9 months). The initiation date of long-term respiratory support was known in 15 of 54 patients, the median was 180 [91; 276] days (5,9 months). Both the start date of long-term respiratory support and the date of death were known in 5 of 54 children; whileit was found that the median time from the initiation of long-term respiratory support to death in these children was 361 [135; 619] day (11,87 months).In a subgroup of 32 children with available date of initiation of long-term respiratory support and / or the date of death, the median time from birth to the combined event was 245,5 [173; 331] days (8,07 months).Conclusion. In the course of a retrospective study, the authors obtained the information on the date of the onset of constant respiratory support and the date of death from the date of birth in the absence of pathogenetic treatment in children with type 1 spinal muscular atrophy. The data obtained in the Russian population are comparable with the published international data. This information can be useful for additional assessment of the health status of patients who received drugs affecting the level of SMN protein in the body, as well as reference data for the development of new approaches to therapy.

Background. Dystrophic myotonia type 1 (DM1) is the most common muscular dystrophy in patients of any age. Myotonia “delayed relaxation of muscle” is the leading symptom in DM1 and can occur at any time after onset disease. Myotonia symptoms and electrical myotonia registration are delayed after onset in patients with congenital and infantile forms of DM1. This makes it difficult to diagnose and prevent fatal complications in these patients in a timely manner. Objective: presentation of the clinical data and results of needle electromyography in patients with DM1 onset in the first decade of the life; determination of the first symptoms of the disease, to estimate the age of myotonia and electrical myotonia manifestation for the optimization of the timely diagnostics of the disease.Materials and methods. 13 patients with DM1 aged from 2 months to 34 years were described. 10 patients underwent needle electromyography with analysis of spontaneous activity and needle EMG pattern. The diagnosis was made on the basis of clinical and paraclinical manifestations of the disease and identification of an increase in CTG repeats (50) in the DMPK gene.Results. The onset with extramuscular signs of respiratory and/or feeding disturbances, dysarthria, school learning disorders, autism spectrum disturbance and “floppy infant syndrome” was noted as the first symptoms of the disease. Clinical myotonia symptoms and electrical manifestations of myotonia were absent in all patients for a long time after the disease onset. DM1 was confirmed in all mothers, however in 5 cases the onset of the disease was later than the first symptoms in patients with congenital and childhood onset forms of DM1.Conclusion. The first symptoms of the congenital and infantile forms of DM1 are not specific and occur in a wide range of diseases. Such discriminating signs of DM1 as clinical myotonia, distal muscle atrophy and electrical myotonia appear much later than the onset disease. In the group of patients before and after the formation of phrasal speech, the presented combinations of symptoms allow diagnostics of the congenital and infantile forms of DM1 at the onset of the disease. In its turn, it allows genetic counseling in burdened families and timely prevention of fatal complications.