Brain MRI Abnormalities, Epilepsy and Intellectual Disability in LAMA2 Related Dystrophy - a Genotype/Phenotype Correlation.

BACKGROUND: LAMA2-related muscular dystrophy is a disorder that causes muscle weakness and varies in severity, from a severe, congenital type to a milder, late-onset form. However, the disease does not only affect the muscles, but has systemic involvement and can lead to alterations such as brain malformation, epilepsy and intellectual disability. OBJECTIVE: Describe the frequency of cortical malformations, epilepsy and intellectual disability in LAMA2-RD in a Brazilian cohort and correlate the neurological findings to genetic and motor function. METHODS: This is an observational study of 52 LAMA2-RD patients, who were divided into motor function subgroups and compared based on brain MRI findings, epilepsy, intellectual disability, and type of variants and variant domains. RESULTS: 44 patients (84.6%) were only able to sit, and 8 patients (15.4%) were able to walk. 10 patients (19.2%) presented with cortical malformations (polymicrogyria, lissencephaly-pachygyria, and cobblestone),10 patients (19.2%) presented with epilepsy, and 8 (15.4%) had intellectual disability. CNS manifestations correlated with a more severe motor phenotype and none of the patients able to walk presented with cortical malformation or epilepsy. There was a relation between gene variants affecting the laminin-α2 LG-domain and the presence of brain malformation (P = 0.016). There was also a relation between the presence of null variants and central nervous system involvement. A new brazilian possible founder variant was found in 11 patients (21,15%) (c.1255del; p. Ile419Leufs*4). CONCLUSION: Cortical malformations, epilepsy and intellectual disability are more frequent among LAMA2-RD patients than previously reported and correlate with motor function severity and the presence of variants affecting the laminin-α2 LG domain. This brings more insight fore phenotype-genotype correlations, shows the importance of reviewing the brain MRI of patients with LAMA2-RD and allows greater attention to the risk of brain malformation, epilepsy, and intellectual disability in those patients with variants that affect the LG domain.

Hypoglycemia in Patients With LAMA2-CMD.

BACKGROUND: Hypoglycemia has been reported in patients with LAMA2-CMD, but the frequency, risk factors, and correlation to genotype/phenotype have not been systematically assessed to date. METHODS: A retrospective cohort study was performed on 48 patients with LAMA2-CMD. Patients were divided into two groups: a hypoglycemic group, with at least one episode of hypoglycemia, and a nonhypoglycemic group. The groups were compared according to gait function, epilepsy, intellectual disability, constipation, gastroesophageal reflux, gastrostomy, weight percentile, scoliosis, the use of a ventilator device, the use of a feeding device, neuromuscular disease swallowing status scale, and type of mutation. RESULTS: Fifteen patients (31.2%) presented with at least one episode of symptomatic hypoglycemia and eight (16.6% of the cohort) had two or more episodes. All patients who had hypoglycemia were in the nonambulant group. We observed a correlation between gait, the use of ventilator and feeding devices, and swallow function with hypoglycemia. Patients with extremely low weight were five times more likely to have recurrent episodes of hypoglycemia. The presence of at least one missense variant appears to be associated with a lower risk of hypoglycemia. CONCLUSION: Patients with LAMA2-CMD are at risk of hypoglycemia. The risk is more relevant in patients with severe phenotype and patients with loss-of-function variants. For patients with extremely low weight, the risk is higher. Blood glucose should be actively measured in patients who are fasting or have infections, and health care providers should be prepared to identify and treat these patients.

Clinical Manifestation of Nebulin-Associated Nemaline Myopathy.

Background and Objectives: Nemaline myopathy (NM) is a genetically heterogeneous inherited myopathy related with at least 12 genes, whereas pathogenic variants in NEB gene are the most common genetic cause. The clinical spectrum of NM caused by NEB pathogenic variants (NM-NEB) is very broad, ranging from mild to severe presentations manifesting with generalized weakness, as well as respiratory and bulbar involvement. There is currently not enough data regarding the progression of the disease. In this study, we present a genotypic and phenotypic spectrum of 33 patients with NM caused by NEB variants (NM-NEB) classified according to age groups and the use of ventilatory support. We focused on interventional support, genotype-phenotype correlation, and association between respiratory, bulbar, and motor systems in groups of patients stratified by age and by the use of ventilatory support (VS). Methods: Clinical and genetic data from patients with NM-NEB followed up in one specialized center were collected through regular consultations. Patients were evaluated regarding motor, bulbar, and respiratory functions. Results: Thirty-three patients with NM-NEB were evaluated consisting of 15 females and 18 males with an average age of 18 (±12) years and a median of 17 (±11) years. 32% of patients with NM-NEB used a G tube, 35% were not able to walk without support, and 55% needed VS. Scoliosis and dysphagia were more common among patients who used VS. Described for the first time, half of the patients presented tongue atrophy in a triple furrow pattern, and the presence of the atrophy was associated with dysphagia. Comparing the patients grouped by age, we found that, proportionally, older patients had more scoliosis and respiratory dysfunction than younger groups, suggesting the progression of the disease in these domains. In addition to that, we showed that VS use was associated with scoliosis and dysphagia. Discussion: NM-NEB is a very debilitating disease. There is an association between scoliosis and respiratory dysfunction while patients using VS have more often scoliosis than the no-VS group. Triple furrow tongue atrophy is a novel and frequent finding, which is directly associated with dysphagia. Grouping patients by age suggested disease stability in motor and swallow function, but a progression in respiratory dysfunction and skeletal deformities. All observations are relevant in the management care of patients with NM.

Effect of the COVID-19 pandemic on patients with inherited neuromuscular disorders.

BACKGROUND: The COVID-19 pandemic has brought substantial challenges for current practices in treating hereditary neuromuscular disorders (hNMDs). However, this infection has not been the only concern for these patients. Social distancing has compromised multidisciplinary assistance and physical activity, and has brought about several mental health issues. We presented a follow-up on 363 patients with hNMDs at a Brazilian tertiary center during the peak of the COVID-19 pandemic. OBJECTIVE: We aimed to show the frequency and severity of SARS-CoV-2 infection among hNMD patients and to demonstrate the effects of the pandemic on life habits, disease progression and multidisciplinary supportive care status. METHODS: Three hundred and sixty-three patients (58% male and 42% female) were followed for three months through three teleconsultations during the peak of the COVID-19 pandemic in Brazil. RESULTS: There were decreases in the numbers of patients who underwent physical, respiratory and speech therapies. For several patients, their appetite (33%) and sleep habits (25%) changed. Physical exercises and therapies were interrupted for most of the patients. They reported new onset/worsening of fatigue (17%), pain (17%), contractions (14%) and scoliosis (7%). Irritability and sleep, weight and appetite changes, and especially diminished appetite and weight loss, were more frequent in the group that reported disease worsening. There was a low COVID-19 contamination rate (0.8%), and all infected patients had a mild presentation. CONCLUSION: The isolation by itself was protective from a COVID-19 infection perspective. However, this isolation might also trigger a complex scenario with life habit changes that are associated with an unfavorable course for the NMD.

The Location of Disease-Causing DES Variants Determines the Severity of Phenotype and the Morphology of Sarcoplasmic Aggregates.

Desmin (DES) is the main intermediate muscle filament that connects myofibrils individually and with the nucleus, sarcolemma, and organelles. Pathogenic variants of DES cause desminopathy, a disorder affecting the heart and skeletal muscles. We aimed to analyze the clinical features, morphology, and distribution of desmin aggregates in skeletal muscle biopsies of patients with desminopathy and to correlate these findings with the type and location of disease-causing DES variants. This retrospective study included 30 patients from 20 families with molecularly confirmed desminopathy from 2 neuromuscular referral centers. We identified 2 distinct patterns of desmin aggregates: well-demarcated subsarcolemmal aggregates and diffuse aggregates with poorly delimited borders. Pathogenic variants located in the 1B segment and the tail domain of the desmin molecule are more likely to present with early-onset cardiomyopathy compared to patients with variants in other segments. All patients with mutations in the 1B segment had well-demarcated subsarcolemmal aggregates, but none of the patients with variants in other desmin segments showed such histological features. We suggest that variants located in the 1B segment lead to well-shaped subsarcolemmal desmin aggregation and cause disease with more frequent cardiac manifestations. These findings will facilitate early identification of patients with potentially severe cardiac syndromes.

Effect of the COVID-19 pandemic on patients with inherited neuromuscular disorders / Efeito da pandemia do COVID-19 em pacientes com doenças neuromusculares hereditárias

ABSTRACT Background The COVID-19 pandemic has brought substantial challenges for current practices in treating hereditary neuromuscular disorders (hNMDs). However, this infection has not been the only concern for these patients. Social distancing has compromised multidisciplinary assistance and physical activity, and has brought about several mental health issues. We presented a follow-up on 363 patients with hNMDs at a Brazilian tertiary center during the peak of the COVID-19 pandemic. Objective We aimed to show the frequency and severity of SARS-CoV-2 infection among hNMD patients and to demonstrate the effects of the pandemic on life habits, disease progression and multidisciplinary supportive care status. Methods Three hundred and sixty-three patients (58% male and 42% female) were followed for three months through three teleconsultations during the peak of the COVID-19 pandemic in Brazil. Results There were decreases in the numbers of patients who underwent physical, respiratory and speech therapies. For several patients, their appetite (33%) and sleep habits (25%) changed. Physical exercises and therapies were interrupted for most of the patients. They reported new onset/worsening of fatigue (17%), pain (17%), contractions (14%) and scoliosis (7%). Irritability and sleep, weight and appetite changes, and especially diminished appetite and weight loss, were more frequent in the group that reported disease worsening. There was a low COVID-19 contamination rate (0.8%), and all infected patients had a mild presentation. Conclusion The isolation by itself was protective from a COVID-19 infection perspective. However, this isolation might also trigger a complex scenario with life habit changes that are associated with an unfavorable course for the NMD.

RESUMO Antecedentes: A Pandemia por COVID-19 tem trazido desafios subtanciais para a prática clínica no tratamento das doenças neuromusculares hereditárias (DNMh). A infecção não tem sido a única preocupação para os pacientes. O distanciamento social tem comprometido a assistência multidisciplinar, atividade física e tem trazido problemas mentais em decorrência do próprio isolamento. Nós apresentamos aqui um seguimento de 363 pacientes com DNMh de um centro terciário Brasileiro durante o pico da Pandemia de Covid-19. Objetivos: Mostrar a frequência e gravidade da infecção por Sars-Cov-2 em pacientes com DNMh e demonstrar os efeitos da pandemia nos hábitos de vida, na progressão da doença e no cuidado multidisciplinary. Métodos Trezentos e sessenta e três pacientes (58% homens and 42% mulheres) foram acompanhados por 3 meses através de 3 teleconsultas durante o pico da Pandemia de Covid-19 no Brasil. Resultados Houve um decréscimo no número de pacientes que faziam terapia física, respiratória e fonoaudiológica. Em muitos pacientes, o apetite (33%) e hábitos do sono (25%) se alteraram. Exercícios físicos e terapias foram interrompidas pela maioria dos pacientes. Physical exercises and therapies were interrupted for most of the patients. Eles relataram piora ou aparecimento de fadiga (17%), dor (17%), retrações (14%), e escoliose (7%). Irritabilidade, mudanças no sono, peso e apetite, sendo principalmente diminuição do apetite e peso foram mais frequentemente encontrados em pacientes que apresentaram piora clinica da doença. Houve uma baixa taxa de contaminação por Covid-19 (0.8%), e todos os pacientes infectado apresentaram quadro clinico leve. Conclusão O isolamento por si só se mostrou protetor na perspectiva de infecção por Covid-19, mas pode desencadear um cenário complexo com mudanças nos hábitos de vida e curso desfavorável da doença de base.

Motor unit number index (MUNIX) in children and adults with 5q-spinal muscular atrophy: Variability and clinical correlations.

Spinal muscular atrophy (SMA) is a motor neuron disease associated with progressive muscle weakness and motor disability. The motor unit number index (MUNIX) is a biomarker used to assess loss of motor units in later-onset SMA patients. Twenty SMA patients (SMA types 3 and 4), aged between 7 and 41 years, were clinically evaluated through the Hammersmith Motor Functional Scale Expanded and the Spinal Muscular Atrophy-Functional Rating Scale. The patients underwent compound motor action potential (CMAP) and MUNIX studies of the right abductor pollicis brevis, abductor digiti minimi and tibialis anterior (TA) muscles. Age-matched healthy controls (n = 20) were enrolled to obtain normative CMAP and MUNIX values from the same muscles. Compared to healthy controls, SMA patients showed significant reductions in MUNIX values among all muscles studied, whereas CMAP showed reductions only in the weaker muscles (abductor digiti minimi and TA). MUNIX variability was significantly higher in the SMA group than in the control group. MUNIX variability in TA correlated with CMAP variability. Motor functional scores correlated with TA MUNIX. The MUNIX study is feasible in later-onset SMA patients, and TA MUNIX values correlate with disease severity in patients with mild motor impairment.

Managing intrathecal administration of nusinersen in adolescents and adults with 5q-spinal muscular atrophy and previous spinal surgery.

BACKGROUND: Spinal muscular atrophy (SMA) is a neurodegenerative disease of lower motor neurons associated with frequent occurrence of spinal deformity. Nusinersen is an antisense oligonucleotide that increases SMN protein level and is administrated by frequent intrathecal lumbar injections. Thus, spinal deformities and previous spinal surgery are important challenges for drug delivery in SMA. OBJECTIVE: To report imaging methods used for Nusinersen injection in SMA patients. METHODS: Nusinersen injection procedures in SMA types 2 and 3 patients who had previous spinal surgery were analyzed retrospectively to describe the imaging and puncture procedures, as well as the occurrence of complications. RESULTS: Nine SMA patients (14 to 50 years old) underwent 57 lumbar punctures for nusinersen injection. Six patients had no interlaminar space available; in five of them, a transforaminal approach was used, and another one underwent a surgery to open a posterior bone window for the injections. Transforaminal puncture was performed using CT scan in three cases and fluoroscopy in the other two, with a similar success rate. One patient in the transforaminal group had post-procedure radiculitis, and another one had vagal reaction (hypotension). In three cases, with preserved interlaminar space, injections were performed by posterior interlaminar puncture, and only one adverse event was reported (post-puncture headache). CONCLUSION: In SMA patients with previous spinal surgery, the use of imaging-guided intervention is necessary for administering intrathecal nusinersen. Transforaminal technique is indicated in patients for whom the interlaminar space is not available, and injections should always be guided by either CT or fluoroscopy.

Intragenic variants in the SMN1 gene determine the clinical phenotype in 5q spinal muscular atrophy.

OBJECTIVE: The aim of the study was to report the proportion of homozygous and compound heterozygous variants in the survival motor neuron 1 (SMN1) gene in a large population of patients with spinal muscular atrophy (SMA) and to correlate the severity of the disease with the presence of specific intragenic variants in SMN1 and with the SMN2 copy number. METHODS: Four hundred fifty Brazilian patients with SMA were included in a retrospective study, and clinical data were analyzed compared with genetic data; the SMN2 copy number was obtained by multiplex ligation-dependent probe amplification and pathogenic variants in SMN1 by next-generation sequencing. RESULTS: Four hundred two patients (89.3%) presented homozygous exon 7-SMN1 deletion, and 48 (10.7%) were compound heterozygous for the common deletion in one allele and a point mutation in the other allele. Recurrent variants in exons 3 and 6 (c.460C>T, c.770_780dup and c.734_735insC) accounted for almost 80% of compound heterozygous patients. Another recurrent pathogenic variant was c.5C>G at exon 1. Patients with c.770_780dup and c.734_735insC had a clinical phenotype correlated with SMN2 copy number, whereas the variants c.460C>T and c.5C>G determined a milder phenotype independently of the SMN2 copies. CONCLUSIONS: Patients with specific pathogenic variants (c.460C>T and c.5C>G) presented a milder phenotype, and the SMN2 copy number did not correlate with disease severity in this group.

Combining neuropsychological tests to improve the assessment of arithmetic difficulties in children with ADHD / Combinando testes neuropsicológicos para melhorar a avaliação de dificuldades aritméticas em crianças com TDAH

Abstract Objective: To compare the ways of evaluating arithmetic skills in Brazilian children with ADHD by combining three validated neuropsychological tests and determining whether they are sensitive to the methylphenidate treatment. Methods: Forty-two children (9‒12 years old) participated in the present study: 20 were children with ADHD (DSM-IV) and 22 were age-matched controls. A classification criterion was used for each test separately and one, for their combination to detect the presence of arithmetic difficulties at two time points: baseline (time 1); and when children with ADHD were taking 0.3‒0.5 mg/kg of methylphenidate (time 2). The study also assessed children's subtraction performance, combining parts of these tests. Results: Separately, the tests were only sensitive to differences between groups without medication. However, by combining the three neuropsychological tests, we observed a difference and detected a reduction in arithmetic difficulties associated with the methylphenidate treatment. The same effects were found in subtraction exercises, which require a borrowing procedure. Conclusions: The present study detected arithmetic difficulties in Brazilian children with ADHD and the effects of methylphenidate. Given this improvement in sensitivity, combining tests could be a promising alternative when working with limited samples.

Resumo Objetivo: Comparar as formas de avaliar as habilidades aritméticas em crianças brasileiras com TDAH, combinando três testes neuropsicológicos validados, e verificar se são sensíveis ao tratamento com metilfenidato. Métodos: Quarenta e duas crianças (9‒12 anos) participaram deste estudo: 20 eram crianças com TDAH (DSM-IV) e 22 eram controles pareados por idade. Usamos um critério de classificação para cada teste separadamente e outro para a combinação entre eles, visando detectar a presença de dificuldades aritméticas em dois momentos: início (tempo 1) e quando as crianças com TDAH estavam tomando 0,3‒0,5 mg/kg de metilfenidato (tempo 2). O estudo também avaliou o desempenho dessas crianças em operações de subtração, combinando partes desses testes. Resultados: Separadamente, os testes foram sensíveis apenas às diferenças entre os grupos sem medicação. Entretanto, ao combinar os três testes neuropsicológicos, foi possível observar uma diferença e detectar uma redução das dificuldades aritméticas associadas ao tratamento com metilfenidato. Os mesmos efeitos foram encontrados em exercícios de subtração que exigem o procedimento de empréstimo. Conclusões: O estudo foi capaz de detectar dificuldades aritméticas em crianças brasileiras com TDAH e os efeitos do metilfenidato. Dada essa melhora na sensibilidade, combinar testes poderia ser uma alternativa promissora ao trabalhar com amostras limitadas.

Combining neuropsychological tests to improve the assessment of arithmetic difficulties in children with ADHD.

OBJECTIVE: To compare the ways of evaluating arithmetic skills in Brazilian children with ADHD by combining three validated neuropsychological tests and determining whether they are sensitive to the methylphenidate treatment. METHODS: Forty-two children (9‒12 years old) participated in the present study: 20 were children with ADHD (DSM-IV) and 22 were age-matched controls. A classification criterion was used for each test separately and one, for their combination to detect the presence of arithmetic difficulties at two time points: baseline (time 1); and when children with ADHD were taking 0.3‒0.5 mg/kg of methylphenidate (time 2). The study also assessed children's subtraction performance, combining parts of these tests. RESULTS: Separately, the tests were only sensitive to differences between groups without medication. However, by combining the three neuropsychological tests, we observed a difference and detected a reduction in arithmetic difficulties associated with the methylphenidate treatment. The same effects were found in subtraction exercises, which require a borrowing procedure. CONCLUSIONS: The present study detected arithmetic difficulties in Brazilian children with ADHD and the effects of methylphenidate. Given this improvement in sensitivity, combining tests could be a promising alternative when working with limited samples.

Clinical features of collagen VI-related dystrophies: A large Brazilian cohort.

OBJECTIVES: Collagen VI-related dystrophies (COL6-RDs) have a broad clinical spectrum and are caused by mutations in the COL6A1, COL6A2 and COL6A3 genes. Despite the clinical variability, two phenotypes are classically recognized: Bethlem myopathy (BM, milder form) and Ullrich congenital muscular dystrophy (UCMD, more severe form), with many patients presenting an intermediate phenotype. In this work, we present clinical and genetic data from 28 patients (27 families), aged 6-38 years (mean of 16.96 years), with COL6-RDs. PATIENTS AND METHODS: Clinical, muscle histology and genetic data are presented. COL6A1, COL6A2 and COL6A3 genes were analyzed by next-generation sequencing (NGS). RESULTS: Homozygous or heterozygous variants were found in COL6A1 (12 families), COL6A2 (12 families) and COL6A3 (3 families). Patients with the severe UCMD phenotype (three cases) had a homogeneous clinical picture characterized by neonatal onset of manifestations, no gait acquisition and a stable course, but with severe respiratory involvement. Most of the patients with the mild UCMD phenotype had neonatal onset of manifestations (88.8 %), delayed motor development (66.6 %), slowly progressive course, pulmonary involvement (55.5 %) and loss of the walking capacity before the age of 10 (66.6 %). In the intermediate group (nine patients), some children had neonatal onset of manifestations (44.5 %) and delayed motor development (88.9 %); but all of them achieved the ability to walk and were still ambulatory. Some patients that had the BM phenotype presented neonatal manifestations (57.1 %); however, all of them had normal motor development and normal pulmonary function. Only one patient from the group of BM lost the walking capacity during the evolution of the disease. Other frequent findings observed in all groups were joint retractions, spinal deformities, distal hyperextensibility, congenital hip dislocation and keloid formation. CONCLUSION: COL6-RDs present variable clinical manifestations, but common findings are helpful for the clinical suspicion. NGS is a valuable approach for diagnosis, providing useful information for the genetic counseling of families.

Congenital fiber type disproportion caused by TPM3 mutation: A report of two atypical cases.

Congenital fiber type disproportion (CFTD) is a rare congenital myopathy subtype defined by slow type 1 hypotrophy in the absence of any other major structural findings such as rods, central nuclei or cores. Dominant missense changes in slow alpha-tropomyosin coded by TPM3 gene are the main cause of the CFTD. There are only a few reports of recessive loss-of-function mutations in TPM3 causing severe Nemaline Myopathy and CFTD. We present two patients harboring TPM3 mutations. The first is a novel homozygous missense variant with a mild CFTD clinical phenotype inherited in a recessive fashion. The second is a previously reported heterozygous mutation presenting within pronounced early axial involvement and dropped head. This report expands the genotype-phenotype correlation in the TPM3 myopathy showing a recessive mutation causing a mild clinical phenotype and also shows that TPM3 mutations should be part of the investigation in patients with dropped head.

Cognitive performance of children with spinal muscular atrophy: A systematic review.

Spinal muscular atrophy (SMA) is genetic and progressive, caused by large bi-allelic deletions in the SMN1 gene, or the association of a large deletion and a null variant. OBJECTIVE: To evaluate the evidence about cognitive outcomes in spinal muscular atrophy (SMA). METHODS: Searches on the PUBMED/Medline, Web of Knowledge and Scielo databases retrieved 26 studies (1989 to 2019, descriptors "spinal muscular atrophy" and "cognition"). Nine studies were selected according to the eligibility criteria: (1) cognition tested in individuals with SMA; (2) written in English or Spanish. The Risk of Bias in Non-Randomized Studies of Interventions was used to describe design, bias, participants, evaluation protocol and main findings. This study was registered on the International prospective register of systematic reviews (PROSPERO). RESULTS: Three studies described normal cognition. In another three studies, cognitive outcomes were above average. Cognitive impairment was found in three studies. Poor cognitive performance was more frequently reported in studies that were recent, included children with SMA type I and that employed visual/auditory attention and executive function tests. Protocols and cognitive domains varied, precluding metanalysis. CONCLUSION: The severity of motor impairment may be related to cognitive outcomes: studies that included a higher number/percentage of children with SMA type I found cognitive impairment. The establishment of gold-standard protocols is necessary. Further studies should compare the cognitive outcomes of subjects with SMA types I to IV.

A atrofia muscular espinhal (SMA) é genética e progressiva, causada por grandes deleções bi-alélicas no gene SMN1, ou pela associação de uma grande deleção e uma variante nula. OBJETIVO: Avaliar as evidências sobre o desempenho cognitivo na atrofia muscular espinhal (AME). MÉTODOS: Pesquisas nas bases de dados PUBMED/ Medline, Web of Knowledge e Scielo localizaram 26 estudos (1989 a 2019, descritores "atrofia muscular espinhal" e "cognição"). Nove estudos foram selecionados de acordo com os critérios de elegibilidade: (1) testaram a cognição em pessoas com AME; (2) escritos em inglês/espanhol. A avaliação do risco de viés em estudos com intervenções não-randomizadas foi utilizada para descrever o desenho experimental, viés, amostra, protocolo de avaliação e principais achados. Este estudo foi aprovado no Registro Internacional Prospectivo de Revisões Sistemáticas (PROSPERO). RESULTADOS: Em três estudos, foi registrado que a cognição estava preservada. Em três estudos, o desempenho cognitivo estava acima da média. O comprometimento cognitivo foi encontrado em três estudos. Desempenho cognitivo pobre foi mais frequentemente relatado em estudos recentes, estudos que incluíram crianças com AME tipo I e estudos que incluíram atenção visual/auditiva e testes de função executiva. Protocolos e domínios cognitivos variaram muito, portanto não foi possível a realização de metanálise. CONCLUSÃO: A gravidade do comprometimento motor pode estar relacionada ao desempenho cognitivo: estudos que incluíram maior número/porcentagem de crianças com AME tipo I encontraram alterações no desempenho cognitivo. O estabelecimento de protocolos padrão-ouro é necessário. Novos estudos devem comparar o desempenho cognitivo de pessoas com AME tipos I a IV, ou seja, com diferenças no prognóstico e no desempenho motor.

Cognitive performance of children with spinal muscular atrophy: A systematic review / Desempenho cognitivo de crianças com atrofia muscular espinhal: uma revisão sistemática

ABSTRACT Spinal muscular atrophy (SMA) is genetic and progressive, caused by large bi-allelic deletions in the SMN1 gene, or the association of a large deletion and a null variant. Objective: To evaluate the evidence about cognitive outcomes in spinal muscular atrophy (SMA). Methods: Searches on the PUBMED/Medline, Web of Knowledge and Scielo databases retrieved 26 studies (1989 to 2019, descriptors "spinal muscular atrophy" and "cognition"). Nine studies were selected according to the eligibility criteria: (1) cognition tested in individuals with SMA; (2) written in English or Spanish. The Risk of Bias in Non-Randomized Studies of Interventions was used to describe design, bias, participants, evaluation protocol and main findings. This study was registered on the International prospective register of systematic reviews (PROSPERO). Results: Three studies described normal cognition. In another three studies, cognitive outcomes were above average. Cognitive impairment was found in three studies. Poor cognitive performance was more frequently reported in studies that were recent, included children with SMA type I and that employed visual/auditory attention and executive function tests. Protocols and cognitive domains varied, precluding metanalysis. Conclusion: The severity of motor impairment may be related to cognitive outcomes: studies that included a higher number/percentage of children with SMA type I found cognitive impairment. The establishment of gold-standard protocols is necessary. Further studies should compare the cognitive outcomes of subjects with SMA types I to IV.

RESUMO A atrofia muscular espinhal (SMA) é genética e progressiva, causada por grandes deleções bi-alélicas no gene SMN1, ou pela associação de uma grande deleção e uma variante nula. Objetivo: Avaliar as evidências sobre o desempenho cognitivo na atrofia muscular espinhal (AME). Métodos: Pesquisas nas bases de dados PUBMED/ Medline, Web of Knowledge e Scielo localizaram 26 estudos (1989 a 2019, descritores "atrofia muscular espinhal" e "cognição"). Nove estudos foram selecionados de acordo com os critérios de elegibilidade: (1) testaram a cognição em pessoas com AME; (2) escritos em inglês/espanhol. A avaliação do risco de viés em estudos com intervenções não-randomizadas foi utilizada para descrever o desenho experimental, viés, amostra, protocolo de avaliação e principais achados. Este estudo foi aprovado no Registro Internacional Prospectivo de Revisões Sistemáticas (PROSPERO). Resultados: Em três estudos, foi registrado que a cognição estava preservada. Em três estudos, o desempenho cognitivo estava acima da média. O comprometimento cognitivo foi encontrado em três estudos. Desempenho cognitivo pobre foi mais frequentemente relatado em estudos recentes, estudos que incluíram crianças com AME tipo I e estudos que incluíram atenção visual/auditiva e testes de função executiva. Protocolos e domínios cognitivos variaram muito, portanto não foi possível a realização de metanálise. Conclusão: A gravidade do comprometimento motor pode estar relacionada ao desempenho cognitivo: estudos que incluíram maior número/porcentagem de crianças com AME tipo I encontraram alterações no desempenho cognitivo. O estabelecimento de protocolos padrão-ouro é necessário. Novos estudos devem comparar o desempenho cognitivo de pessoas com AME tipos I a IV, ou seja, com diferenças no prognóstico e no desempenho motor.

Clinical variability of early-onset congenital myasthenic syndrome due to biallelic RAPSN mutations in Brazil.

Mutations in RAPSN are an important cause of congenital myasthenic syndrome (CMS), leading to endplate acetylcholine receptor deficiency. We present three RAPSN early-onset CMS patients (from a Brazilian cohort of 61 CMS patients). Patient 1 and patient 2 harbor the mutation p.N88K in homozygosity, while patient 3 harbors p.N88K in compound heterozygosity with another pathogenic variant (p.V165M; c.493G ≥ A). At onset, patient 3 presented with more severe symptoms compared to the other two, showing generalized weakness and repeated episodes of respiratory failure in the first years of life. During adolescence, she became gradually less symptomatic and does not require medication anymore, presenting better long-term outcomes than patients 1 and 2. This case series illustrates the variability of RAPSN early-onset CMS, with patient 3, despite severe onset, revealing an almost complete reversal of myasthenic symptoms, not limited to apneic episodes. Moreover, it suggests that RAPSN CMS may be underdiagnosed in non-European countries.

Therapeutic advances in 5q-linked spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a severe and clinically-heterogeneous motor neuron disease caused, in most cases, by a homozygous mutation in the SMN1 gene. Regarding the age of onset and motor involvement, at least four distinct clinical phenotypes have been recognized. This clinical variability is, in part, related to the SMN2 copy number. By now, only supportive therapies have been available. However, promising specific therapies are currently being developed based on different mechanisms to increase the level of SMN protein; in particular, intrathecal antisense oligonucleotides that prevent the skipping of exon 7 during SMN2 transcription, and intravenous SMN1 insertion using viral vector. These therapeutic perspectives open a new era in the natural history of the disease. In this review, we intend to discuss the most recent and promising therapeutic strategies, with special consideration to the pathogenesis of the disease and the mechanisms of action of such therapies.