Cardiac findings in pediatric patients with spinal muscular atrophy types 2 and 3

Troponin T is elevated in a relevant proportion of patients with 5q-associated spinal muscular atrophy

Troponin T concentration (TNT) is commonly considered a marker of myocardial damage. However, elevated concentrations have been demonstrated in numerous neuromuscular disorders, pointing to the skeletal muscle as a possible extracardiac origin. The aim of this study was to determine disease-related changes of TNT in 5q-associated spinal muscular atrophy (SMA) and to screen for its biomarker potential in SMA. We therefore included 48 pediatric and 45 adult SMA patients in this retrospective cross-sequential observational study. Fluid muscle integrity and cardiac markers were analyzed in the serum of treatment-naïve patients and subsequently under disease-modifying therapies. We found a TNT elevation in 61% of SMA patients but no elevation of the cardiospecific isoform Troponin I (TNI). TNT elevation was more pronounced in children and particularly infants with aggressive phenotypes. In adults, TNT correlated to muscle destruction and decreased under therapy only in the subgroup with elevated TNT at baseline. In conclusion, TNT was elevated in a relevant proportion of patients with SMA with emphasis in infants and more aggressive phenotypes. Normal TNI levels support a likely extracardiac origin. Although its stand-alone biomarker potential seems to be limited, exploring TNT in SMA underlines the investigation of skeletal muscle integrity markers.

Troponin T in spinal and bulbar muscular atrophy (SBMA)

Serum biomarkers that might detect clinical progression are currently lacking for Spinal and bulbar muscular atrophy (SBMA), thus limiting the effectiveness of possible future pharmacological trials. Elevation of cardiac troponin T (cTnT) unrelated to myocardial damage in a motor neuron (MN) disease as amyotrophic lateral sclerosis (ALS) was associated to disease severity. We enrolled 47 SBMA patients and 5 Spinal muscular atrophy (SMA) type 3 adult patients as control group; each SBMA patient was evaluated at baseline and at one-year follow-up visit. Demographic and clinical data including functional scores (SBMAFRS) were collected; serum was collected as standard of care and tested for cardiac troponins. Levels of cTnT but not cTnI were increased in SBMA with respect to reference values; unlike other neuromuscular diseases, SMA patients had overall normal cTnT values. Median cTnT concentrations did not change after one year and values were correlated to motor function, particularly with lower limb subdomain, at baseline only. Variations of cTnT and of SBMAFRS were unrelated. The cautiously promising results of cTnT as potential biomarker should undergo a more extensive clinical validation, including studies with longer follow-up period. When evaluating SBMA patients for a potential cardiac damage cTnI testing should be coupled or preferred to cTnT.

Cardiac function evaluation in children with spinal muscular atrophy: A case-control study

BACKGROUND

Spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by degeneration of lower motor neurons, resulting in progressive muscle weakness and atrophy. However, little is known regarding the cardiac function of children with SMA.

METHODS

We recruited SMA patients younger than 18 years of age from January 1, 2022, to April 1, 2022, in the First Affiliated Hospital of Sun Yat-sen University. All patients underwent a comprehensive cardiac evaluation before treatment, including history taking, physical examination, blood tests of cardiac biomarkers, assessment of echocardiography and electrocardiogram. Age/gender-matched healthy volunteers were recruited as controls.

RESULTS

A total of 36 SMA patients (26 with SMA type 2 and 10 with SMA type 3) and 40 controls were enrolled in the study. No patient was clinically diagnosed with heart failure. Blood tests showed elevated values of creatine kinase isoenzyme M and isoenzyme B (CK-MB) mass and high-sensitivity cardiac troponin T (hs-cTnT) in spinal muscular atrophy (SMA) patients. Regarding echocardiographic parameters, SMA children were detected with lower global left and right ventricular longitudinal strain, abnormal diastolic filling velocities of trans-mitral and trans-tricuspid flow. The results revealed no clinical heart dysfunction in SMA patients, but subclinical ventricular dysfunction was seen in SMA children including the diastolic function and myocardial performance. Some patients presented with elevated heart rate and abnormal echogenicity of aortic valve or wall. Among these SMA patients, seven patients (19.4%) had scoliosis. The Cobb's angles showed a significant negative correlation with LVEDd/BSA, but no correlation with other parameters, suggesting that mild scoliosis did not lead to significant cardiac dysfunction.

CONCLUSIONS

Our findings warrant increased attention to the cardiac status and highlight the need to investigate cardiac interventions in SMA children.

AAV9-mediated SMN gene therapy rescues cardiac desmin but not lamin A/C and elastin dysregulation in Smn2B/- spinal muscular atrophy mice

Structural, functional and molecular cardiac defects have been reported in spinal muscular atrophy (SMA) patients and mouse models. Previous quantitative proteomics analyses demonstrated widespread molecular defects in the severe Taiwanese SMA mouse model. Whether such changes are conserved across different mouse models, including less severe forms of the disease, has yet to be established. Here, using the same high-resolution proteomics approach in the less-severe Smn2B/- SMA mouse model, 277 proteins were found to be differentially abundant at a symptomatic timepoint (post-natal day (P) 18), 50 of which were similarly dysregulated in severe Taiwanese SMA mice. Bioinformatics analysis linked many of the differentially abundant proteins to cardiovascular development and function, with intermediate filaments highlighted as an enriched cellular compartment in both datasets. Lamin A/C was increased in the cardiac tissue, whereas another intermediate filament protein, desmin, was reduced. The extracellular matrix (ECM) protein, elastin, was also robustly decreased in the heart of Smn2B/- mice. AAV9-SMN1-mediated gene therapy rectified low levels of survival motor neuron protein and restored desmin levels in heart tissues of Smn2B/- mice. In contrast, AAV9-SMN1 therapy failed to correct lamin A/C or elastin levels. Intermediate filament proteins and the ECM have key roles in cardiac function and their dysregulation may explain cardiac impairment in SMA, especially since mutations in genes encoding these proteins cause other diseases with cardiac aberration. Cardiac pathology may need to be considered in the long-term care of SMA patients, as it is unclear whether currently available treatments can fully rescue peripheral pathology in SMA.

Surgical correction of a ventricular septal defect in a child with spinal muscular atrophy type 2 treated with nusinersen sodium: a case report

INTRODUCTION

Spinal muscular atrophy (SMA) is a severe, inherited neuromuscular disorder characterized by progressive muscle weakness and atrophy. Cardiac pathology co-existence is reported more frequently in the severely affected patient groups. Structural heart anomalies, mainly septal, and outflow tract defects are commonly observed pathologies.

CASE PRESENTATION

We herein report the case of a 23 days-old female patient with the diagnosis of spinal muscular atrophy type 2 complicated with structural heart defects. Successful pulmonary banding, and at the age of 17 months, subsequent surgical atrial and ventricular septal defect closure were performed on our patient who was under treatment of Nusinersen Sodium. Post-operative recovery was uncomplicated. Cardiac assessments were normal, and the patient was neurologically improving in her recent follow-up.

CONCLUSION

In the literature, there are no reported cases of successful surgical repair of heart defects in spinal muscular atrophy patients. These patients can be perceived as risky surgical candidates with suboptimal postoperative recovery given the unfavorable disease prognosis of SMA in untreated patients. We report our promising experience with a SMA type 2 patient undergoing a disease-modifying medical treatment. The SMA patients under treatment may be potential candidates for successful surgical cardiac correction given their overall improved prognosis.

Comorbid pathology in children with type II–III spinal muscular atrophy on the background of acquired deformities of the skeleton bones

Spinal muscular atrophy (SMA) is a severe genetic disease associated with impaired SMN protein synthesis and degeneration of alpha motor neurons in the spinal cord. Developing neurogenic kyphoscoliosis and deformity of the chest against the background of symmetrical muscular hypotension sharply limit the activity of patients, worsening the concomitant diseases.Purpose. The study aims at determining the comorbid background of children with type II–III spinal muscular atrophy who underwent inpatient treatment for acquired skeletal bone deformities.Material and methods. A retrospective analysis of the data was carried out for the period from 2017 to 2021 based on the medical records of 31 children. The study group included 10 girls and 21 boys; 16 children were with type II and 15 — with type III spinal muscular atrophy. The following were assessed: comorbidity, neurological status, hemodynamic parameters, echocardiography, spirometry, laboratory research data.Results. In our study, comorbidity was associated with nutritional status (19% of patients overweight, 29% underweight), mental retardation (3%), gastroesophageal reflux disease (19%), diseases of the ENT organs (16%), eyes (19%), heart and lungs (93%). For health reasons, 61% of children required the use of non-invasive ventilation, and 71% of insufflator-aspirators. Limited motor abilities were registered based on the HFMSE and GMFCS scales, dysphagia based on the EDACS scale. A biochemical blood test revealed a low level of creatinine.Conclusion. Patients with spinal muscular atrophy require multidisciplinary care in diagnosis, treatment and rehabilitation. The use of objective rating scales, instrumental and laboratory methods of examination allow for a comprehensive analysis of the potential of children with spinal muscular atrophy, to select effective, family-oriented treatment regimens. Serum creatinine as a biomarker for the severity of muscle denervation makes it possible to monitor the progression of spinal muscular atrophy and predict response to treatment.

Serum leptin levels in children and adolescents with spinal muscular atrophy types 2 and 3✰

AIM

It has been reported that in patients with spinal muscular atrophy (SMA), lower levels of motor function are associated with hyperleptinemia. Additionally, hyperleptinemia has been found to be more frequent in underweight SMA patients. Therefore, we aimed to analyze serum leptin levels in patients with SMA.

METHOD

This was a cross-sectional study of pediatric patients (2-19 years old) with SMA types 2 and 3. The investigations included anthropometric measurements, assessment of pubertal status, motor function evaluation using the Hammersmith Functional Motor Scale - Expanded (HFMSE), and serum leptin levels.

RESULTS

In total, 37 patients (22 with type 2 and 15 with type 3 SMA) were included in the study. The male-to-female ratio was 1:1.3 and 62.2% of patients were prepubertal. No statistically significant correlation was found between the HFMSE score and leptin levels, r_s(35) = 0.24, p = 0.15. There was, however, a strong positive relationship between the body mass index (BMI) z-score and leptin levels, r_s(35) = 0.87, p < 0.001.

CONCLUSION

Serum leptin levels do not seem to be a useful marker of disease severity in children and adolescents with types 2 and 3 SMA. As in the general pediatric population, leptin levels are strongly correlated with BMI, which is a surrogate measure of body fat.

The alteration of left ventricular strain in later-onset spinal muscular atrophy children

Background

Patients with spinal muscular atrophy (SMA) may suffer from multisystem injury, including an impaired cardiovascular system. However, M-mode echocardiography, the current dominant echocardiographic modality, is limited in the detection of myocardial injury. We considered the use of left ventricular strain imaging in detecting myocardial injury and explored the serum lipid profile related to cardiovascular disease in later-onset SMA children.

Methods

A case-control study involving 80 patients with later-onset SMA and 80 age-, gender-, and body surface area-matched control children was conducted in a single tertiary pediatric hospital in China. Data on the left ventricular strain measured using two-dimensional speckle tracking echocardiography, left ventricular function parameters assessed by M-mode echocardiography, and serum lipid profile of these two groups were retrospectively collected for differential analysis.

Results

The mean age of the 80 SMA patients were (6.87 ± 2.87) years, of which 46 were type 2 and 34 were type 3 patients. The global longitudinal strain (GLS) of the SMA group (−18.7 ± 2.9%, p < 0.001) was lower than that of the control group; the time to peak longitudinal strain (TTPLS) of the SMA group (22.9 ± 13.6 ms, p < 0.001) was higher than that of the control group, while left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), measured by the Teichholz method of M-mode echocardiography, showed no significant differences between the two groups. In addition, independent indicators for cardiovascular risk, including total cholesterol (TC)/HDL, low-density lipoprotein (LDL)/HDL, and Apo B/Apo A1 levels, were higher in SMA children than in the control group.

Conclusion

Compared with healthy controls, later-onset SMA children presented with reduced GLS and prolonged TTPLS while the LVEF and LVFS values were within normal range. In particular, whether a reduced GLS or prolonged TTPLS in later-onset SMA compared to the control group can predict the risk of future cardiomyopathy remains to be investigated.

Safety Monitoring of Gene Therapy for Spinal Muscular Atrophy with Onasemnogene Abeparvovec -A Single Centre Experience

BACKGROUND

Recently gene therapy with onasemnogene abeparvovec has been approved for the treatment of spinal muscular atrophy (SMA). As the experience from clinical trials is limited, there are still uncertainties for which patient population the treatment can be considered safe and effective.

METHODS

We report our experience with eight consecutive patients with SMA who were treated with the standard dose of onasemnogene abeparvovec (1.1×1014 vg/kg) at the University Hospital Bonn, Germany. All patients received prophylactic immunosuppression with 1 mg/kg/d prednisolone for four weeks starting on the day before gene therapy.

RESULTS

We treated eight patients (4 male, 4 female, age range 10-37 months) with a body weight between 7.1 and 11.9 kg. All patients had 2 or 3 copies of the SMN2-gene and were previously treated with nusinersen. Following treatment with onasemnogene abeparvovec all patients showed a temporary increase of the body temperature and an increase of transaminase levels. In all but one patient it was necessary to increase or prolong the standard steroid dose to control the immune response. In one severe case, liver damage was associated with impaired liver function. This patient received a steroid pulse therapy for five days. Blood counts revealed asymptomatic thrombocytopenia (<150×109/L) in 6/8 patients and a significant increase of monocytes following gene therapy. Liver values and blood counts returned to almost normal levels during the post-treatment observation period. Troponin I increased above normal limit in 4/8 patients but was not associated with any abnormalities on cardiac evaluation.

CONCLUSIONS

In a broader spectrum of patients, treatment with onasemnogene abeparvovec was associated with a higher rate of adverse events. In our cases it was possible to control the immune response by close monitoring and adaptation of the immunosuppressive regimen. Further research is needed to better understand the immune response following gene therapy and ideally to identify patients at risk for a more severe reaction.

Glucose and lipid metabolism disorders in children and adolescents with spinal muscular atrophy types 2 and 3

We aimed to estimate the prevalence of glucose and lipid metabolism disorders in children and adolescents with spinal muscular atrophy (SMA) types 2 and 3. A cross-sectional study was conducted. Medical history, anthropometric measurements, pubertal status, blood chemistry (glucose and insulin levels, lipid profile, aminotransferases, and hemoglobin A1c [HbA1c]), and liver ultrasound were obtained in all patients. Oral glucose tolerance test was performed in those with body mass index (BMI) >25th percentile or glucose or HbA1c levels in the prediabetic range. A total of 37 patients with SMA (22 type 2, 15 type 3) with a median age of 8.5 years (range 2-18.9 years) were included. Eleven patients (29.7%) met the criteria for prediabetes, but none had overt type 2 diabetes. Dyslipidemia was detected in 11 patients (29.7%), and 4 (10.8%) had hepatic steatosis on ultrasound. Sixteen patients (43.2%) had at least one abnormal finding (prediabetes, dyslipidemia, or hepatic steatosis); all but one were non-ambulatory and 12 (75%) had BMI ≥85th percentile. One young child developed fasting hypoglycemia. Our results suggest that non-ambulatory overweight/obese SMA patients are particularly prone to abnormalities in glucose and lipid metabolism. Young underweight patients might develop fasting hypoglycemia.