Terapia genica: ¿Dónde estamos?, ¿A dónde vamos? / Gene therapy: Where are we? Where are we going?

Resumen La terapia génica ha logrado avances significativos en el tratamiento de enfermedades genéticas, especial mente en enfermedades raras y monogénicas. Se han desarrollado y aprobado terapias génicas para tratar en fermedades como la atrofia muscular espinal, brindando esperanza a los pacientes y demostrando la eficacia de esta terapia. Actualmente, se están realizando numerosos ensayos clínicos para evaluar la seguridad y eficacia de la terapia génica en diversas enfermedades, particularmente en el campo de la neurología pediátrica. Estos estudios están generando datos alentadores y contribuyen al conoci miento sobre cómo mejorar las técnicas de terapia génica. A pesar de los avances, la terapia génica enfrenta desafíos importantes. Es una terapia costosa y téc nicamente compleja, lo que limita su accesibilidad. Además, aspectos como la entrega eficiente de genes, la respuesta inmunológica a los vectores y la duración de la respuesta terapéutica requieren mejoras. se está investigando activamente. En cuanto al futuro de la terapia génica, se espera que los avances en tecnología de edición génica, como CRISPR-Cas9, permitan una mayor precisión y eficiencia en la modificación de genes. Se espera que la investigación en vectores de terapia génica mejore la capacidad de entrega y la seguridad de los tratamientos. Se están desarrollando nuevas ge neraciones de vectores virales y no virales que podrían superar las limitaciones actuales y permitir una admi nistración más eficiente y precisa de genes terapéuticos.

Abstract Gene therapy has achieved significant advancements in the treatment of genetic diseases, especially in rare and monogenic diseases. Gene therapies have been de veloped and approved to treat diseases such as spinal muscular atrophy, offering hope to patients and dem onstrating the effectiveness of this therapy. Currently, numerous clinical trials are being conduct ed to evaluate the safety and efficacy of gene therapy in various diseases, particularly in the field of pediatric neurology. These studies are generating encouraging data and contributing to the knowledge on how to im prove gene therapy techniques. Despite the advancements, gene therapy faces significant challenges. It is a costly and technically complex therapy, limiting its accessibility. Addition ally, aspects such as efficient gene delivery, immune response to vectors, and duration of therapeutic re sponse require improvements and are actively being investigated. Regarding the future of gene therapy, advances in gene editing technology, such as CRISPR-Cas9, are ex pected to allow for greater precision and efficiency in gene modification. Research on gene therapy vectors is expected to en hance the delivery capacity and safety of treatments. New generations of viral and non-viral vectors are be ing developed that could overcome current limitations and enable more efficient and precise administration of therapeutic genes.

[Gene therapy: Where are we? Where are we going?] / Terapia génica: ¿dónde estamos?, ¿a dónde vamos?

Gene therapy has achieved significant advancements in the treatment of genetic diseases, especially in rare and monogenic diseases. Gene therapies have been developed and approved to treat diseases such as spinal muscular atrophy, offering hope to patients and demonstrating the effectiveness of this therapy. Currently, numerous clinical trials are being conducted to evaluate the safety and efficacy of gene therapy in various diseases, particularly in the field of pediatric neurology. These studies are generating encouraging data and contributing to the knowledge on how to improve gene therapy techniques. Despite the advancements, gene therapy faces significant challenges. It is a costly and technically complex therapy, limiting its accessibility. Additionally, aspects such as efficient gene delivery, immune response to vectors, and duration of therapeutic response require improvements and are actively being investigated. Regarding the future of gene therapy, advances in gene editing technology, such as CRISPR-Cas9, are expected to allow for greater precision and efficiency in gene modification. Research on gene therapy vectors is expected to enhance the delivery capacity and safety of treatments. New generations of viral and non-viral vectors are being developed that could overcome current limitations and enable more efficient and precise administration of therapeutic genes.

La terapia génica ha logrado avances significativos en el tratamiento de enfermedades genéticas, especialmente en enfermedades raras y monogénicas. Se han desarrollado y aprobado terapias génicas para tratar enfermedades como la atrofia muscular espinal, brindando esperanza a los pacientes y demostrando la eficacia de esta terapia. Actualmente, se están realizando numerosos ensayos clínicos para evaluar la seguridad y eficacia de la terapia génica en diversas enfermedades, particularmente en el campo de la neurología pediátrica. Estos estudios están generando datos alentadores y contribuyen al conocimiento sobre cómo mejorar las técnicas de terapia génica. A pesar de los avances, la terapia génica enfrenta desafíos importantes. Es una terapia costosa y técnicamente compleja, lo que limita su accesibilidad. Además, aspectos como la entrega eficiente de genes, la respuesta inmunológica a los vectores y la duración de la respuesta terapéutica requieren mejoras. se está investigando activamente. En cuanto al futuro de la terapia génica, se espera que los avances en tecnología de edición génica, como CRISPR-Cas9, permitan una mayor precisión y eficiencia en la modificación de genes. Se espera que la investigación en vectores de terapia génica mejore la capacidad de entrega y la seguridad de los tratamientos. Se están desarrollando nuevas generaciones de vectores virales y no virales que podrían superar las limitaciones actuales y permitir una administración más eficiente y precisa de genes terapéuticos.

Decoding the transcriptome of Duchenne muscular dystrophy to the single nuclei level reveals clinical-genetic correlations.

Duchenne muscular dystrophy is a genetic disease produced by mutations in the dystrophin gene characterized by early onset muscle weakness leading to severe and irreversible disability. The cellular and molecular consequences of the lack of dystrophin in humans are only partially known, which is crucial for the development of new therapies aiming to slow or stop the progression of the disease. Here we have analyzed quadriceps muscle biopsies of seven DMD patients aged 2 to 4 years old and five age and gender matched controls using single nuclei RNA sequencing (snRNAseq) and correlated the results obtained with clinical data. SnRNAseq identified significant differences in the proportion of cell population present in the muscle samples, including an increase in the number of regenerative fibers, satellite cells, and fibro-adipogenic progenitor cells (FAPs) and a decrease in the number of slow fibers and smooth muscle cells. Muscle samples from the younger patients with stable mild weakness were characterized by an increase in regenerative fibers, while older patients with moderate and progressive weakness were characterized by loss of muscle fibers and an increase in FAPs. An analysis of the gene expression profile in muscle fibers identified a strong regenerative signature in DMD samples characterized by the upregulation of genes involved in myogenesis and muscle hypertrophy. In the case of FAPs, we observed upregulation of genes involved in the extracellular matrix regeneration but also several signaling pathways. Indeed, further analysis of the potential intercellular communication profile showed a dysregulation of the communication profile in DMD samples identifying FAPs as a key regulator of cell signaling in DMD muscle samples. In conclusion, our study has identified significant differences at the cellular and molecular levels in the different cell populations present in skeletal muscle samples of patients with DMD compared to controls.

A novel phenotype of AChR-deficiency syndrome with predominant facial and distal weakness resulting from the inclusion of an evolutionary alternatively-spliced exon in CHRNA1.

Primary acetylcholine receptor deficiency is the most common subtype of congenital myasthenic syndrome, resulting in reduced amount of acetylcholine receptors expressed at the muscle endplate and impaired neuromuscular transmission. AChR deficiency is caused mainly by pathogenic variants in the ε-subunit of the acetylcholine receptor encoded by CHRNE, although pathogenic variants in other subunits are also seen. We report the clinical and molecular features of 13 patients from nine unrelated kinships with acetylcholine receptor deficiency harbouring the CHRNA1 variant NM_001039523.3:c.257G>A (p.Arg86His) in homozygosity or compound heterozygosity. This variant results in the inclusion of an alternatively-spliced evolutionary exon (P3A) that causes expression of a non-functional acetylcholine receptor α-subunit. We compare the clinical findings of this group to the other cases of acetylcholine receptor deficiency within our cohort. We report differences in phenotype, highlighting a predominant pattern of facial and distal weakness in adulthood, predominantly in the upper limbs, which is unusual for acetylcholine receptor deficiency syndromes, and more in keeping with slow-channel syndrome or distal myopathy. Finally, we stress the importance of including alternative exons in variant analysis to increase the probability of achieving a molecular diagnosis.

[Guillain-Barré syndrome and other autoimmune neurophaties: current therapy]. / Síndrome de Guillain-Barré y otras neuropatías autoinmunes: tratamiento actual.

Guillain-Barré syndrome (GBS) is characterized by rapidly progressive and generally ascending symmetrical muscle weakness, accompanied by decreased or absent osteotendinous reflexes. The inflammatory process may affect the myelin or the axon. There are 4 clinical forms of GBS: 1) acute inflammatory demyelinating polyradiculoneuropathy, 2) acute motor axonal neuropathy, 3) acute sensory and motor axonal neuropathy, and 4) the Miller-Fisher variant, which is characterized by ophthalmoplegia, ataxia and areflexia, with little muscle weakness. Diagnosis is based on the albumin-cytological dissociation observed at the end of the first week after the onset of symptoms and may persist until the third week, as well as on the specific neurophysiological alterations of each clinical form. The treatment of GBS will depend on the degree of severity, if the patient presents grade IV or less according to the Paradiso scale, it will be treated with Ig IV, if it presents grade V, the use of plasmapheresis and/or immunoadbosorption is recommended. In severe axonal cases, the use of corticosteroid bolus is recommended in initial stages. There is a clinical picture that overlaps GBS and chronic demyelinating polyneuropathy related to antibodies against neurophysin and contactin, in this case the appropriate therapy is rituximab.

El síndrome de Guillain-Barré (SGB) se caracteriza por debilidad muscular simétrica rápidamente progresiva y generalmente ascendente, acompañada de disminución o ausencia de reflejos osteotendinosos. El proceso inflamatorio puede afectar a la mielina o al axón. Existen 4 formas clínicas de SGB: 1) polirradiculoneuropatía desmielinizante inflamatoria aguda, 2) neuropatía axonal motora aguda, 3) neuropatía axonal sensitiva y motora aguda, y 4) la variante Miller-Fisher, que se caracteriza por oftalmoplejía, ataxia y arreflexia, con escasa debilidad muscular. El diagnóstico se basa en la disociación albúmino-citológica que se observa a final de la primera semana del inicio de los síntomas y puede persistir hasta la tercera semana, así como en las alteraciones neurofisiológicas específicas de cada forma clínica. El tratamiento el SGB, dependerá de la gravedad, si el paciente presenta grado IV o menor según la escala de Paradiso, se tratará con Ig IV, si presenta grado V, se recomienda el uso de plasmaféresis y/o inmunoadbosorción. En los casos axonales graves se recomienda el uso de bolus de corticoides en etapas iniciales. Existe un cuadro clínico que solapa SGB y polineuropatía desmielinizante crónica relacionado con anticuerpos contra neurofisina y contactina, en este caso la terapia adecuada es rituximab.

Sleep breathing disorders in pediatric patients with spinal muscular atrophy 2.

OBJECTIVES: The study is aimed to analyze both sleep architecture and prevalence of sleep-disordered breathing (SDB), in a group of patients with type 2 spinal muscular atrophy (SMA), considering motor dysfunction, and compare them with age-matched controls. METHODS: Eighteen SMA type 2 patients (nine males median age 9.5 (4-17) years) and eighteen controls (fourteen males, median age 8,5 (1-16) years) underwent nocturnal polysomnography. SMA type 2 patients were evaluated with motor scales; Hammersmith Functional Motor Scale Expanded (HFMSE), Revised upper limb model (ULMR) and Egen Klassification Scale Version 2 (EK2). Parents/tutors completed two pediatric sleep questionnaires (respiratory subscale from Chervin Pediatric Sleep Questionnaire and Bruni's Sleep Disturbance Scale for Children). RESULTS: When compared with controls, SMA type 2 patients showed no significant differences in age (9.72 ± 4.2 vs 8.22 ± 3.9 (p = 0.28), gender 9 (9 men (50%) vs 14 (77,8%) (p = 0.083) and nutritional status; Body Mass Index (BMI) (16.4 (12.2-34.8) vs 17.6 (4.4-24.2) (p = 0.83). Apnea Hypopnea Index (AHI) was statistically higher in SMA type 2 patients (6.7 ± 6.2 vs 0.4 ± 0.3) (p < 0.001). The SpO2 mean values in cases were (96% ± 1.4) vs (97.5% ± 1.2) (p = 0.007). TcPCO2 median value (41,5 mmHg; (range 34-47.2) in the SMA type-2 patients within normal reference values. Only one motor scale; Hammersmith Functional Motor Scale Expanded (HFMSE) showed a negative correlation with AHI (r = -0.132). CONCLUSIONS: Patients affected by SMA type 2 presented significantly higher apnea-hypopnea indices than controls; differences in sleep architecture identified include: decreased total sleep time, increased percentage of stage N1 of NREM sleep as well as increased sleep fragmentation seen in the SMA type 2 group, due to respiratory related arousals. We would like to point out that validated pediatric sleep questionnaires in general population, may not be useful tools when screening for SDB in these patients. This should be taken into consideration in clinical practice and in the elaboration of future clinical guidelines for these patients.