Titin copy number variations associated with dominant inherited phenotypes.

BACKGROUND: Titinopathies are caused by mutations in the titin gene (TTN). Titin is the largest known human protein; its gene has the longest coding phase with 364 exons. Titinopathies are very complex neuromuscular pathologies due to the variable age of onset of symptoms, the great diversity of pathological and muscular impairment patterns (cardiac, skeletal muscle or mixed) and both autosomal dominant and recessive modes of transmission. Until now, only few CNVs in TTN have been reported without clear genotype-phenotype associations. METHODS: Our study includes eight families with dominant titinopathies. We performed next-generation sequencing or comparative genomic hybridisation array analyses and found CNVs in the TTN gene. We characterised these CNVs by RNA sequencing (RNAseq) analyses in six patients' muscles and performed genotype-phenotype inheritance association study by combining the clinical and biological data of these eight families. RESULTS: Seven deletion-type CNVs in the TTN gene were identified among these families. Genotype and RNAseq results showed that five deletions do not alter the reading frame and one is out-of-reading frame. The main phenotype identified was distal myopathy associated with contractures. The analysis of morphological, clinical and genetic data and imaging let us draw new genotype-phenotype associations of titinopathies. CONCLUSION: Identifying TTN CNVs will further increase diagnostic sensitivity in these complex neuromuscular pathologies. Our cohort of patients enabled us to identify new deletion-type CNVs in the TTN gene, with unexpected autosomal dominant transmission. This is valuable in establishing new genotype-phenotype associations of titinopathies, mainly distal myopathy in most of the patients.

Clinical Phenotype of Pediatric and Adult Patients With Spinal Muscular Atrophy With Four SMN2 Copies: Are They Really All Stable?

OBJECTIVE: The aim of this study was to provide an overview of the clinical phenotypes associated with 4 SMN2 copies. METHODS: Clinical phenotypes were analyzed in all the patients with 4 SMN2 copies as part of a nationwide effort including all the Italian pediatric and adult reference centers for spinal muscular atrophy (SMA). RESULTS: The cohort includes 169 patients (102 men and 67 women) with confirmed 4 SMN2 copies (mean age at last follow-up = 36.9 ± 19 years). Six of the 169 patients were presymptomatic, 8 were classified as type II, 145 as type III (38 type IIIA and 107 type IIIB), and 8 as type IV. The remaining 2 patients were asymptomatic adults identified because of a familial case. The cross-sectional functional data showed a reduction of scores with increasing age. Over 35% of the type III and 25% of the type IV lost ambulation (mean age = 26.8 years ± 16.3 SD). The risk of loss of ambulation was significantly associated with SMA type (p < 0.0001), with patients with IIIB and IV less likely to lose ambulation compared to type IIIA. There was an overall gender effect with a smaller number of women and a lower risk for women to lose ambulation. This was significant in the adult (p = 0.009) but not in the pediatric cohort (p = 0.43). INTERPRETATION: Our results expand the existing literature on natural history of 4 SMN2 copies confirming the variability of phenotypes in untreated patients, ranging from type II to type IV and an overall reduction of functional scores with increasing age. ANN NEUROL 2023;94:1126-1135.

Early treatment of type II SMA slows rate of progression of scoliosis.

BACKGROUND: Type II spinal muscular atrophy (SMA) often leads to scoliosis in up to 90% of cases. While pharmacological treatments have shown improvements in motor function, their impact on scoliosis progression remains unclear. This study aims to evaluate potential differences in scoliosis progression between treated and untreated SMA II patients. METHODS: Treatment effect on Cobb's angle annual changes and on reaching a 50° Cobb angle was analysed in treated and untreated type II SMA patients with a minimum 1.5-year follow-up. A sliding cut-off approach identified the optimal treatment subpopulation based on age, Cobb angle and Hammersmith Functional Motor Scale Expanded at the initial visit. Mann-Whitney U-test assessed statistical significance. RESULTS: There were no significant differences in baseline characteristics between the untreated (n=46) and treated (n=39) populations. The mean Cobb angle variation did not significantly differ between the two groups (p=0.4). Optimal cut-off values for a better outcome were found to be having a Cobb angle <26° or an age <4.5 years. When using optimal cut-off, the treated group showed a lower mean Cobb variation compared with the untreated group (5.61 (SD 4.72) degrees/year vs 10.05 (SD 6.38) degrees/year; p=0.01). Cox-regression analysis indicated a protective treatment effect in reaching a 50° Cobb angle, significant in patients <4.5 years old (p=0.016). CONCLUSION: This study highlights that pharmacological treatment, if initiated early, may slow down the progression of scoliosis in type II SMA patients. Larger studies are warranted to further investigate the effectiveness of individual pharmacological treatment on scoliosis progression in this patient population.

Determining minimal clinically important differences in the Hammersmith Functional Motor Scale Expanded for untreated spinal muscular atrophy patients: An international study.

BACKGROUND AND PURPOSE: Spinal muscular atrophy (SMA) is a rare and progressive neuromuscular disorder with varying severity levels. The aim of the study was to calculate minimal clinically important difference (MCID), minimal detectable change (MDC), and values for the Hammersmith Functional Motor Scale Expanded (HFMSE) in an untreated international SMA cohort. METHODS: The study employed two distinct methods. MDC was calculated using distribution-based approaches to consider standard error of measurement and effect size change in a population of 321 patients (176 SMA II and 145 SMA III), allowing for stratification based on age and function. MCID was assessed using anchor-based methods (receiver operating characteristic [ROC] curve analysis and standard error) on 76 patients (52 SMA II and 24 SMA III) for whom the 12-month HFMSE could be anchored to a caregiver-reported clinical perception questionnaire. RESULTS: With both approaches, SMA type II and type III patients had different profiles. The MCID, using ROC analysis, identified optimal cutoff points of -2 for type II and -4 for type III patients, whereas using the standard error we found the optimal cutoff points to be 1.5 for improvement and -3.2 for deterioration. Furthermore, distribution-based methods uncovered varying values across age and functional status subgroups within each SMA type. CONCLUSIONS: These results emphasize that the interpretation of a single MCID or MDC value obtained in large cohorts with different functional status needs to be made with caution, especially when these may be used to assess possible responses to new therapies.

Experience of a 2-year spinal muscular atrophy NBS pilot study in Italy: towards specific guidelines and standard operating procedures for the molecular diagnosis.

BACKGROUND: Spinal muscular atrophy (SMA) is due to the homozygous absence of SMN1 in around 97% of patients, independent of the severity (classically ranked into types I-III). The high genetic homogeneity, coupled with the excellent results of presymptomatic treatments of patients with each of the three disease-modifying therapies available, makes SMA one of the golden candidates to genetic newborn screening (NBS) (SMA-NBS). The implementation of SMA in NBS national programmes occurring in some countries is an arising new issue that the scientific community has to address. We report here the results of the first Italian SMA-NBS project and provide some proposals for updating the current molecular diagnostic scenario. METHODS: The screening test was performed by an in-house-developed qPCR assay, amplifying SMN1 and SMN2. Molecular prognosis was assessed on fresh blood samples. RESULTS: We found 15 patients/90885 newborns (incidence 1:6059) having the following SMN2 genotypes: 1 (one patient), 2 (eight patients), 2+c.859G>C variant (one patient), 3 (three patients), 4 (one patient) or 6 copies (one patient). Six patients (40%) showed signs suggestive of SMA at birth. We also discuss some unusual cases we found. CONCLUSION: The molecular diagnosis of SMA needs to adapt to the new era of the disease with specific guidelines and standard operating procedures. In detail, SMA diagnosis should be felt as a true medical urgency due to therapeutic implications; SMN2 copy assessment needs to be standardised; commercially available tests need to be improved for higher SMN2 copies determination; and the SMN2 splicing-modifier variants should be routinely tested in SMA-NBS.

Type I spinal muscular atrophy patients treated with nusinersen: 4-year follow-up of motor, respiratory and bulbar function.

BACKGROUND: We report the 4-year follow-up in type I patients treated with nusinersen and the changes in motor, respiratory and bulbar function in relation to subtype, age and SMN2 copy number. METHODS: The study included SMA 1 patients with at least one assessment after 12, 24 and 48 months from the first dose of nusinersen. The assessments used were Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) and the Hammersmith Infant Neurological Examination (HINE-II). RESULTS: Forty-eight patients, with ages ranging from 7 days to 12 years (mean 3.3 years, SD 3.6 years) were included in the study. The CHOP INTEND and HINE-II scores significantly increased between baseline and 48 months (p < 0.001). When age at starting treatment subgroups (<210 days, <2 years, 2-4 years, 5-11 years, ≥12 years) were considered, the CHOP INTEND increased significantly in patients younger than 4 years at treatment, while the HINE-2 increased significantly in patients younger than 2 years at treatment. In a mixed-model analysis, age, nutritional and respiratory status were predictive of changes on both scales while SMN2 copy number and decimal classification were not. CONCLUSIONS: Our results confirm the safety profile previously reported and support the durability of the efficacy of nusinersen at 4 years with an overall stability or mild improvement and no evidence of deterioration over a long period of time.

Financial cost and quality of life of patients with spinal muscular atrophy identified by symptoms or newborn screening.

AIM: To compare the societal financial costs and quality of life (QoL) of untreated patients with spinal muscular atrophy (SMA) and treated patients identified because they presented symptoms or were identified by early testing (sibling or newborn screening). METHOD: Data from two different sources were used: data collected prospectively in untreated patients from 2016 to 2018 and data collected during a prospective follow-up study from 2018 to 2021. Patients or their caregiver completed a questionnaire that included questions on direct medical and non-medical costs, indirect non-medical costs, and health-related QoL. RESULTS: Data (median; range) were available for 149 patients (93 untreated - 10 years; 2 years-59 years), 42 patients (6 years 3 months; 9 months-58 years) treated after presenting with symptoms, and 14 patients (1 year 7 months; 5 months-2 years) treated after early diagnosis. Total costs were lower in untreated patients due to the high cost of drugs used in treated patients. Costs were lower for treated patients who were identified by early testing than for treated patients identified because they presented with symptoms. In all groups, patients with two SMN2 copies had higher costs than those with more copies. INTERPRETATION: Early patient identification and treatment offer the opportunity to reduce the total societal costs of SMA where treatments are available for presymptomatic and postsymptomatic patients. WHAT THIS PAPER ADDS: Untreated patients with spinal muscular atrophy had lower total financial costs than treated patients. Total financial costs were lower for treated patients identified by early screening than for treated patients identified after symptom onset. Direct financial costs excluding treatment were much lower in treated patients identified by early screening. Hospitalization costs were much lower in patients identified by early screening.

COSTO ECONÓMICO Y CALIDAD DE VIDA DE PACIENTES CON ATROFIA MUSCULAR ESPINAL IDENTIFICADOS POR SÍNTOMAS O CRIBADO NEONATAL: OBJETIVO: Comparar los costos financieros sociales y la calidad de vida (QoL) de pacientes no tratados con atrofia muscular espinal (AME) y pacientes tratados, identificados porque presentaron síntomas o fueron identificados mediante pruebas tempranas (cribado de hermanos o recién nacidos). MÉTODO: Se utilizaron datos de dos fuentes diferentes: datos recopilados prospectivamente en pacientes no tratados de 2016 a 2018 y datos recopilados durante un estudio de seguimiento prospectivo de 2018 a 2021. Los pacientes o sus cuidadores completaron un cuestionario que incluía preguntas sobre cuestiones médicas y no médicas directas. -costos médicos, costos indirectos no médicos y calidad de vida relacionada con la salud. RESULTADOS: Los datos (mediana; rango) estaban disponibles para 149 pacientes (93 sin tratamiento - 10 años; 2 años - 59 años), 42 pacientes (6 años 3 meses; 9 meses - 58 años) tratados después de presentar síntomas y 14 pacientes (1 año 7 meses; 5 meses-2 años) tratados tras un diagnóstico precoz. Los costos totales fueron menores en los pacientes no tratados debido al alto costo de los medicamentos utilizados en los pacientes tratados. Los costos fueron más bajos para los pacientes tratados que fueron identificados mediante pruebas tempranas que para los pacientes tratados identificados porque presentaban síntomas. En todos los grupos, los pacientes con dos copias de SMN2 tuvieron costos más altos que aquellos con más copias. INTERPRETACIÓN: La identificación y el tratamiento tempranos de los pacientes ofrecen la oportunidad de reducir los costos sociales totales de la AME, en lugares donde los tratamientos están disponibles para pacientes presintomáticos y postsintomáticos.

HDAC inhibitors tune miRNAs in extracellular vesicles of dystrophic muscle-resident mesenchymal cells.

We show that extracellular vesicles (EVs) released by mesenchymal cells (i.e., fibro-adipogenic progenitors-FAPs) mediate microRNA (miR) transfer to muscle stem cells (MuSCs) and that exposure of dystrophic FAPs to HDAC inhibitors (HDACis) increases the intra-EV levels of a subset of miRs, which cooperatively target biological processes of therapeutic interest, including regeneration, fibrosis, and inflammation. Increased levels of miR-206 in EVs released by FAPs of muscles from Duchenne muscular dystrophy (DMD) patients or mdx mice exposed to HDACi are associated with enhanced regeneration and decreased fibrosis. Consistently, EVs from HDACi-treated dystrophic FAPs can stimulate MuSC activation and expansion ex vivo, and promote regeneration, while inhibiting fibrosis and inflammation of dystrophic muscles, upon intramuscular transplantation in mdx mice, in vivo. AntagomiR-mediated blockade of individual miRs reveals a specific requirement of miR-206 for EV-induced expansion of MuSCs and regeneration of dystrophic muscles, and indicates that cooperative activity of HDACi-induced miRs accounts for the net biological effect of these EVs. These data point to pharmacological modulation of EV content as novel strategy for therapeutic interventions in muscular dystrophies.

INPP5K and SIL1 associated pathologies with overlapping clinical phenotypes converge through dysregulation of PHGDH.

Marinesco-Sjögren syndrome is a rare human disorder caused by biallelic mutations in SIL1 characterized by cataracts in infancy, myopathy and ataxia, symptoms which are also associated with a novel disorder caused by mutations in INPP5K. While these phenotypic similarities may suggest commonalties at a molecular level, an overlapping pathomechanism has not been established yet. In this study, we present six new INPP5K patients and expand the current mutational and phenotypical spectrum of the disease showing the clinical overlap between Marinesco-Sjögren syndrome and the INPP5K phenotype. We applied unbiased proteomic profiling on cells derived from Marinesco-Sjögren syndrome and INPP5K patients and identified alterations in d-3-PHGDH as a common molecular feature. d-3-PHGDH modulates the production of l-serine and mutations in this enzyme were previously associated with a neurological phenotype, which clinically overlaps with Marinesco-Sjögren syndrome and INPP5K disease. As l-serine administration represents a promising therapeutic strategy for d-3-PHGDH patients, we tested the effect of l-serine in generated sil1, phgdh and inpp5k a+b zebrafish models, which showed an improvement in their neuronal phenotype. Thus, our study defines a core phenotypical feature underpinning a key common molecular mechanism in three rare diseases and reveals a common and novel therapeutic target for these patients.

Body mass index in type 2 spinal muscular atrophy: a longitudinal study.

The aim of this retrospective study was to review body mass index (BMI) in a large cohort of Italian pediatric type 2 spinal muscular atrophy (SMA) patients, aged between 0 and 20 years and to establish possible differences in relation to a number of variables such as ventilation, motor function, and survival motor neuron 2 gene copies. Cross-sectional data were collected from 102 patients for a total of 344 visits. Standard growth charts for height and weight were used as reference, with age adjusted BMI calculated using the Center for Disease and Prevention Children's BMI Tool. In the 344 visits, weight ranged between 3.90 and 83 kg, and the BMI between 8.4 and 31.6 with a BMI/age z-scores < - 2SD present in 28% and BMI/age z-scores > + 2SD in 9% of the measurements. The BMI/age z-scores were relatively stable < 5 years of age with an increasing number of patients < - 2SD after the age of 5, and a wider range of BMI/age z-scores after the age of 13. A difference on the BMI/age z-scores was found among the different age subgroups (< 5, 5-12, ≥ 13 years). A multivariate analysis in 58 patients with longitudinal assessments showed that baseline BMI/age z-scores and gender were significantly contributing to the changes while other variables were not. CONCLUSION: Our results confirm that careful surveillance of weight and BMI/age z-scores is needed in type 2 SMA. Further studies, including assessments of chewing and swallowing and of lean/fat body mass, will help to better understand the possible mechanisms underlying weight issues. WHAT IS KNOWN: • Feeding difficulties have been reported in a few studies and were invariably found in patients with type 1 SMA. • Type 2 SMA patients often have low BMI with a relevant number of patients requiring tube feeding. WHAT IS NEW: • Reduction in BMI/age z-score overtime appeared to depend on baseline BMI/age z-score and gender. • Patients with a low BMI/age z-score were at higher risk of developing further reduction.

Spinal muscular atrophy: state of the art and new therapeutic strategies.

Spinal muscular atrophy (SMA) is a severe disorder of motor neurons and the most frequent cause of genetic mortality, due to respiratory complications. We are facing an exciting era with three available therapeutic options in a disease considered incurable for more than a century. However, the availability of effective approaches has raised up ethical, medical, and financial issues that are routinely faced by the SMA community. Each therapeutic strategy has its weaknesses and strengths and clinicians need to know them to optimize clinical care. In this review, the state of the art and the results and challenges of the new SMA therapeutic strategies are highlighted.

Novel Splicing Mutation in MTM1 Leading to Two Abnormal Transcripts Causes Severe Myotubular Myopathy.

X-linked myotubular myopathy (XLMTM) is a severe form of centronuclear myopathy, characterized by generalized weakness and respiratory insufficiency, associated with pathogenic variants in the MTM1 gene. NGS targeted sequencing on the DNA of a three-month-old child affected by XLMTM identified the novel hemizygous MTM1 c.1261-5T>G intronic variant, which interferes with the normal splicing process, generating two different abnormal transcripts simultaneously expressed in the patient's muscular cells. The first aberrant transcript, induced by the activation of a cryptic splice site in intron 11, includes four intronic nucleotides upstream of exon 12, resulting in a shift in the transcript reading frame and introducing a new premature stop codon in the catalytic domain of the protein (p.Arg421SerfsTer7). The second aberrant MTM1 transcript, due to the lack of recognition of the 3' acceptor splice site of intron 11 from the spliceosome complex, leads to the complete skipping of exon 12. We expanded the genotypic spectrum of XLMTM underlying the importance of intron−exons boundaries sequencing in male patients affected by XLMTM.

Clinical Variability in Spinal Muscular Atrophy Type III.

OBJECTIVE: We report natural history data in a large cohort of 199 patients with spinal muscular atrophy (SMA) type III assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE). The aim of the study was to establish the annual rate and possible patterns of progression according to a number of variables, such as age of onset, age at assessment, SMN2 copy number, and functional status. METHODS: HFMSE longitudinal changes were assessed using piecewise linear mixed-effects models. The dependency in the data due to repeated measures was accounted for by a random intercept per individual and an unstructured covariance R matrix was used as correlation structure. An additional descriptive analysis was performed for 123 patients, for a total of 375 12-month assessments. RESULTS: A break point at age 7 years was set for the whole cohort and for SMA IIIA and IIIB. Age, SMA type, and ambulatory status were significantly associated with changes in mean HFMSE score, whereas gender and SMN2 copy number were not. The increase in response before the break point of age 7 years is significant only for SMA IIIA (ß = 1.79, p < 0.0001). After the break point, the change in the rate of HFMSE score significantly decrease for both SMA IIIA (ß = -1.15, p < 0.0001) and IIIB (ß = -0.69, p = 0.002). INTERPRETATION: Our findings contribute to the understanding of the natural history of SMA type III and will be helpful in the interpretation of the real-world data of patients treated with commercially available drugs. ANN NEUROL 2020;88:1109-1117.

Age-related sensory neuropathy in patients with spinal muscular atrophy type 1.

INTRODUCTION/AIMS: Spinal muscular atrophy type 1 (SMA 1) is a devastating motor neuron disorder that leads to progressive muscle weakness, respiratory failure and premature death. Although sensory electrophysiological changes have been anecdotally found in pediatric SMA 1 patients, the age of onset of sensory neuropathy remains unknown. METHODS: Sensory nerve conduction studies of the median and sural nerves were performed in 28 consecutive SMA 1 patients of different ages. Sensory nerve conduction velocities and sensory nerve action potential (SNAP) amplitudes recorded in these patients were compared with those obtained from 93 healthy subjects stratified by age. RESULTS: SNAP amplitudes decreased with increasing age in the sural and median nerves, without any significant difference between upper and lower limbs. DISCUSSION: Our data suggest that sural and median nerve SNAP amplitudes are normal in younger patients, while an axonal neuropathy appears in older ones.

New genotype-phenotype correlations in a large European cohort of patients with sarcoglycanopathy.

Sarcoglycanopathies comprise four subtypes of autosomal recessive limb-girdle muscular dystrophies (LGMDR3, LGMDR4, LGMDR5 and LGMDR6) that are caused, respectively, by mutations in the SGCA, SGCB, SGCG and SGCD genes. In 2016, several clinicians involved in the diagnosis, management and care of patients with LGMDR3-6 created a European Sarcoglycanopathy Consortium. The aim of the present study was to determine the clinical and genetic spectrum of a large cohort of patients with sarcoglycanopathy in Europe. This was an observational retrospective study. A total of 33 neuromuscular centres from 13 different European countries collected data of the genetically confirmed patients with sarcoglycanopathy followed-up at their centres. Demographic, genetic and clinical data were collected for this study. Data from 439 patients from 13 different countries were collected. Forty-three patients were not included in the analysis because of insufficient clinical information available. A total of 159 patients had a confirmed diagnosis of LGMDR3, 73 of LGMDR4, 157 of LGMDR5 and seven of LGMDR6. Patients with LGMDR3 had a later onset and slower progression of the disease. Cardiac involvement was most frequent in LGMDR4. Sixty per cent of LGMDR3 patients carried one of the following mutations, either in a homozygous or heterozygous state: c.229C>T, c.739G>A or c.850C>T. Similarly, the most common mutations in LMGDR5 patients were c.525delT or c.848G>A. In LGMDR4 patients the most frequent mutation was c.341C>T. We identified onset of symptoms before 10 years of age and residual protein expression lower than 30% as independent risk factors for losing ambulation before 18 years of age, in LGMDR3, LGMDR4 and LGMDR5 patients. This study reports clinical, genetic and protein data of a large European cohort of patients with sarcoglycanopathy. Improving our knowledge about these extremely rare autosomal recessive forms of LGMD was helped by a collaborative effort of neuromuscular centres across Europe. Our study provides important data on the genotype-phenotype correlation that is relevant for the design of natural history studies and upcoming interventional trials in sarcoglycanopathies.

Muscle inflammatory pattern in alpha- and gamma-sarcoglycanopathies.

AIM: Since the immune system plays a role in the pathogenesis of several muscular dystrophies, we aim to characterize several muscular inflammatory features in α- (LGMD R3) and γ-sarcoglycanopathies (LGMD R5). MATERIALS AND METHODS: We explored the expression of major histocompatibility complex class I molecules (MHCI), and we analyzed the composition of the immune infiltrates in muscle biopsies from 10 patients with LGMD R3 and 8 patients with LGMD R5, comparing the results to Duchenne muscular dystrophy patients (DMD). RESULTS: A consistent involvement of the immune response was observed in sarcoglycanopathies, although it was less evident than in DMD. LGMD R3-R5 and DMD shared an abnormal expression of MHCI, and the composition of the muscular immune cell infiltrate was comparable. CONCLUSION: These findings might serve as a rationale to fine-tune a disease-specific immunomodulatory regimen, particularly relevant in view of the rapid development of gene therapy for sarcoglycanopathies.

Respiratory Needs in Patients with Type 1 Spinal Muscular Atrophy Treated with Nusinersen.

OBJECTIVE: To evaluate the effects of nusinersen on respiratory function of patients with type 1 spinal muscular atrophy. STUDY DESIGN: Observational, longitudinal cohort study. We collected respiratory data from 118 children with type 1 spinal muscular atrophy and differing pulmonary requirements and conducted a semistructured qualitative interview among a subsample of caregivers at baseline, 6 months, and 10 months after the first nusinersen treatment. Patients were stratified according to ventilation modalities and age at study entry. RESULTS: Most patients in our cohort remained stable (84/109 = 77%). More than 80% of the children treated before age 2 years survived, in contrast to the lower survival reported in natural history studies, and did so without tracheostomy or noninvasive ventilation (NIV) ≥16 hours. In those less than 2 years old, only 3 patients shifted from NIV ≤10 hours to NIV >10 hours, and the other 3 reduced the hours of NIV required. Most of the older patients remained stable; this included not only those on tracheostomy or NIV >10 hours but also 75% of those on NIV ≤10 hours. CONCLUSIONS: Our results suggest that nusinersen may produce some improvement in the progression of respiratory impairment, both in terms of survival and need for respiratory support ≥16 hours, especially before the age of 2 years.

Nusinersen in type 1 spinal muscular atrophy: Twelve-month real-world data.

OBJECTIVE: The aim of the study was to report 12-month changes after treatment with nusinersen in a cohort of 85 type I spinal muscular atrophy patients of ages ranging from 2 months to 15 years and 11 months. METHODS: All patients were assessed using the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) and the Hammersmith Infant Neurological Examination-Section 2 (HINE-2). RESULTS: Two of the 85 patients had 1 SMN2 copy, 61 had 2 copies, and 18 had 3 copies. In 4 patients the SMN2 copy number was not available. At baseline, the mean CHOP INTEND scores ranged between 0 and 52 (mean = 15.66, standard deviation [SD] = ±13.48), and the mean HINE-2 score was between 0 and 5 (mean = 0.69, SD = ±1.23). There was a difference between baseline and the 12-month scores on both the CHOP INTEND and the HINE-2 for the whole group (p < 0.001), the subgroups with 2 SMN2 copies (p < 0.001), and those with 3 SMN2 copies (p < 0.001). The difference was found not only in patients younger than 210 days at baseline (p < 0.001) but also in those younger than 5 years on the CHOP INTEND and younger than 2 years on the HINE-2. INTERPRETATION: Our results, expanding the age range and the severity of type I patients treated with nusinersen over 1 year, provide additional data on the range of efficacy of the drug that will be helpful in making an informed decision on whether to start treatment in patients of different ages and severity. ANN NEUROL 2019;86:443-451.

Cardiac and Neuromuscular Features of Patients With LMNA-Related Cardiomyopathy.

Background: Mutations in the LMNA (lamin A/C) gene have been associated with neuromuscular and cardiac manifestations, but the clinical implications of these signs are not well understood. Objective: To learn more about the natural history of LMNA-related disease. Design: Observational study. Setting: 13 clinical centers in Italy from 2000 through 2018. Patients: 164 carriers of an LMNA mutation. Measurements: Detailed cardiologic and neurologic evaluation at study enrollment and for a median of 10 years of follow-up. Results: The median age at enrollment was 38 years, and 51% of participants were female. Neuromuscular manifestations preceded cardiac signs by a median of 11 years, but by the end of follow-up, 90% of the patients had electrical heart disease followed by structural heart disease. Overall, 10 patients (6%) died, 14 (9%) received a heart transplant, and 32 (20%) had malignant ventricular arrhythmias. Fifteen patients had gait loss, and 6 had respiratory failure. Atrial fibrillation and second- and third-degree atrioventricular block were observed, respectively, in 56% and 51% of patients with combined cardiac and neuromuscular manifestations and 37% and 33% of those with heart disease only. Limitations: Some of the data were collected retrospectively. Neuromuscular manifestations were more frequent in this analysis than in previous studies. Conclusion: Many patients with an LMNA mutation have neurologic symptoms by their 30s and develop progressive cardiac manifestations during the next decade. A substantial proportion of these patients will have life-threatening neurologic or cardiologic conditions. Primary Funding Source: None.

Clinical-genetic features and peculiar muscle histopathology in infantile DNM1L-related mitochondrial epileptic encephalopathy.

Mitochondria are highly dynamic organelles, undergoing continuous fission and fusion. The DNM1L (dynamin-1 like) gene encodes for the DRP1 protein, an evolutionary conserved member of the dynamin family, responsible for fission of mitochondria, and having a role in the division of peroxisomes, as well. DRP1 impairment is implicated in several neurological disorders and associated with either de novo dominant or compound heterozygous mutations. In five patients presenting with severe epileptic encephalopathy, we identified five de novo dominant DNM1L variants, the pathogenicity of which was validated in a yeast model. Fluorescence microscopy revealed abnormally elongated mitochondria and aberrant peroxisomes in mutant fibroblasts, indicating impaired fission of these organelles. Moreover, a very peculiar finding in our cohort of patients was the presence, in muscle biopsy, of core like areas with oxidative enzyme alterations, suggesting an abnormal distribution of mitochondria in the muscle tissue.